Device for harvesting direct light and diffuse light from a light source

ABSTRACT

Device for harvesting light from a light source, comprising: First photovoltaic cell having an upper surface, a lower surface, and an array of optical passages therein. Array of optical concentrating elements above the upper surface defining a light acceptance area, each being associated with one of the optical passages, and being structured/arranged to concentrate direct light towards theretowards. Concentrated direct light passing through the first photovoltaic cell via an optical passage and exiting as a non-parallel light beam. Array of optical redirecting elements below the lower surface, each being associated with one of the optical passages; each receiving the light beam from the optical passage with which it is associated and redirecting it optically towards a second photovoltaic cell. Diffuse light passing through the array of optical concentrating elements to upper surface of first photovoltaic cell. Second photovoltaic cell having an active area being smaller than the light acceptance area.

CROSS-REFERENCE

The present application claims the benefit of and priority to U.S.Provisional Patent Application Ser. No. 62/022,078, filed Jul. 8, 2014,entitled “Device for Harvesting Direct Light and Diffuse Light from aLight Source”; the contents of which are incorporated herein byreference in their entirety for all purposes.

FIELD

The present technology relates to devices for harvesting direct lightand diffuse light from a light source.

BACKGROUND

For many reasons, there has been a growth in the development oftechnologies used to harness renewable sources of energy as analternative to the generation of energy via combustion of hydrocarbons.One such renewable source of energy that has seen some attention issolar energy.

Devices used to harvest solar energy have been known in the art for sometime. The most common of such devices are relatively large flat-panelsolar panel assemblies. Such solar panels typically comprise a series offlat “single-junction” crystalline silicon photovoltaic cells that aremechanically and electrically connected together to form a large panelassembly. That panel assembly is then mounted on a supporting structure.Light impinging on the panel assembly enters the photovoltaic cells forharvesting thereby. Solar panel assemblies of this type have been usedfor some time and remain in use today.

Such solar panel assembles are not suitable for use in many instancesowing to the fact that the efficiency of the photovoltaic cells thereofin converting sunlight into electrical energy is relatively low. Thus,in some instances, only a small amount of usable electrical energy wouldbe generated, which would not be sufficient to meet the electricalrequirements of the particular intended application. In other instances,a large number of such solar panel assemblies would be required togenerate a particular desired amount of electricity, rendering suchelectricity more expensive to generate than via another method ofelectrical power generation.

To attempt to overcome this difficulty, high-efficiency photovoltaiccells (“HE-PV cells”) (e.g. triple junction cells) were developed. Astheir name suggests, such HE-PV cells are materially more efficient atconverting sunlight into electrical energy than are the conventionalsingle-junction photovoltaic cells referred to above. The HE-PV cellsare also, however, significantly more expensive to manufacture thanconventional single-junction photovoltaic cells. So much so that inorder to for it to be economically feasible to use such HE-PV cells in asolar electricity generation application where cost is an issue (whichis most applications), only an HE-PV cell of a very small size (relativeto the conventional single-junction crystalline silicon photovoltaiccells found in the large flat-panel solar panel assemblies referred toabove) can be used.

This situation has generated an interest in concentrated photovoltaic(CPV) systems. The theory behind a CPV system is to use optical elementsto concentrate sunlight received over a relatively larger area into arelatively smaller area of an HE-PV cell. Since such optical elementsare relatively inexpensive, in theory, their combination with an HE-PVcell of a relatively small size would make solar energy generated bysuch systems economically feasible. (A cost comparison might be made,for example, between the cost of a standard conventional flat-panelsolar panel assembly of a given area and a CPV system having a lightacceptance area of the same given area.)

There is an important drawback of CPV systems. The optical elements usedto concentrate the light impinging on the system have a very smallacceptance angle for any incoming light. (Generally, only light withinthat acceptance angle is accepted by the system for concentration andultimate harvesting, all other light is generally not harvestable by thesystem.) This means that in most CPV systems, generally only directnormal light (typically referred to in the art as direct normalirradiance (DNI)) is accepted by the optical elements thereof and isharvestable by the system. Since the sun moves across the sky during theday, it is not economically feasible to stationarily mount a CPV systemon a support structure. Typically, such a system is mounted with atwo-axis “tracker”, which is a mechanism that reorients the systemthroughout the day to maintain the entrance of light to the opticalelements normal to the sun into order to maximize the amount of DNI thatthe system receives.

However, not all of the total light received from the sun at aparticular location on the Earth by a panel on a tracker (known in theart as global normal irradiance (GNI)) is DNI. Molecules and suspensoidsin the Earth's atmosphere will scatter some of the beam of lightincoming from the sun to produce what is known in the art as “diffuselight” (i.e. non-direct light in that particular situation). The ratioof DNI to GNI (i.e. how much of the sunlight at a particular location isdirect normal sunlight that has not been scattered) varies by locationon the Earth and with time. For example, the ratio will be affected bythen current meteorological conditions at the location on the Earthreceiving the sunlight. On an overcast day in Toronto for example, theratio is zero as all of the light is diffuse sunlight. On a clear sunnywinter day in Toronto, approximately 85% of the sunlight received is DNI(owing to the relative lack of moisture and smog in the air); whereas ona clear sunny summer day in Toronto, approximately 70% of the sunlightreceived is DNI (owing to the greater presence of moisture and smog inthe air).

As was discussed above because of their optical elements' smallacceptance angles, conventional CPV systems are generally incapable ofharvesting diffuse light. Diffuse light is simply lost to a conventionalCPV system, which offsets in part the efficiency gains with respect tothe harvesting of direct sunlight in such systems. This also means thateven with a tracker there is a portion of the GNI that is inaccessibleby the system. For any particular location on the Earth an averageannual DNI and DNI to GNI ratio can be calculated in order to evaluatethe economics of the installation of a conventional CPV system.

In order to potentially improve the economics of a conventional CPVsystem, systems have been proposed in which some diffuse light may alsobe accepted and harvested by the system. In this respect, various“hybrid” systems, being combination of a non-concentrated photovoltaicsystem with concentrated photovoltaic system have been proposed.

One such hybrid system is described in U.S. Patent ApplicationPublication No. US 2010/0126556 A1, published May 27, 2010, entitled“Photovoltaic Concentrator with Auxiliary Cells Collecting DiffuseRadiation”; the abstract of which provides: “High-concentrationphotovoltaic concentrators can utilize much more expensivehigh-efficiency cells because they need so much less of them, but muchof the solar resource is left ungathered thereby. The main cell is atthe focal spot of the concentrator. Low-cost secondary solar cells arenow added to the concentrator, surrounding the main cell. Diffuseskylight and misdirected normal rays irradiate these secondary cells,adding to output. Also, the power plant can have output on cloudy days,unlike conventional concentrators. As cell costs fall relative to othercosts, this system becomes economically superior to both flat plate andconcentrator systems.”

Another such hybrid system is described in U.S. Patent ApplicationPublication No. US 2012/0255594 A1, published Oct. 11, 2012, entitled“Solar Power Generator Module”; the abstract of which provides: “A solarpower generator module includes a first type of photovoltaic cell and asecond type of photovoltaic cell. The second type of photovoltaic cellis different from the first type of photovoltaic cell. The modulefurther includes an optical device adapted to concentrate light onto thefirst type of photovoltaic cell and to transmit diffused light to thesecond type of photovoltaic cell.”

While hybrid systems such as those described in the '556 Publication andthe '594 Publication may be useful, improvements in such hybrid systemsare nonetheless possible.

SUMMARY

It is an object of the present technology to provide an improved devicefor harvesting both direct and diffuse light as compared with at leastsome of the prior art.

It is another object of the present technology to provide a hybriddevice for harvesting sunlight that combines a concentratingphotovoltaic system for harvesting direct sunlight and anon-concentrating photovoltaic system for harvesting diffuse sunlight.

In one of its simplest forms the present technology provides a solarpanel device having a concentrating aspect and non-concentrating aspect.(It should be understood that the description of this extremely simpleembodiment which follows is not intended to be a definition of thepresent technology, but simply an aid to understanding the presenttechnology. Embodiments which are far more complex are within the scopeof the present technology, and are described in the paragraphs thatfollow the present paragraph.) In this simple embodiment, thenon-concentrating aspect uses a solar panel similar to a conventionalnon-concentrating solar panel but having a series of holes in some ofthe panel's non-transparent components. The concentrating aspect usesthis solar panel as a support for a series of lenses located on top ofthe panel and a series of reflectors located on the bottom of the panel.Direct sunlight is focused by the lenses through the holes to thereflectors, which then reflect the light to a high efficiency solar cellfor harvesting. Thus, the direct sunlight is harvested by the device asif the device were a concentrated photovoltaic solar device alone.Diffuse sunlight travels through the concentrating elements to the solarpanel for harvesting. Thus, the diffuse light is harvested by the deviceas if the device were a conventional solar panel alone.

Turning now to consider other embodiments, in more general terms,embodiments of the present technology provide a device for harvestingdirect light and diffuse light from a light source, the devicecomprising: (I) A first photovoltaic cell. The first photovoltaic cellhas an upper surface, a lower surface, and an array of optical passagestherein in optical communication with the upper surface and the lowersurface. (II) An array of optical concentrating elements is above theupper surface of the first photovoltaic cell and defines a lightacceptance area. Each of the optical concentrating elements isassociated with one of the optical passages. Each of the opticalconcentrating elements is structured and arranged to concentrate directlight from the light source impinging on that optical concentratingelement towards the one of the optical passages associated with thatoptical concentrating element. The concentrated direct light passesthrough the first photovoltaic cell via the optical passage and exitsthe first photovoltaic cell via the lower surface as a non-parallel beamof light. Diffuse light from the light source passes through the arrayof optical concentrating elements to the upper surface of the firstphotovoltaic cell and enters the first photovoltaic cell for harvestingthereby. (III) An array of optical redirecting elements is below thelower surface of the first photovoltaic cell. Each of the redirectingelements is associated with one of the optical passages. Each of theredirecting elements receives the beam of light from the optical passagewith which that redirecting element is associated and redirects the beamof light optically towards a second photovoltaic cell for harvestingthereby. The second photovoltaic cell has an active area receiving thebeams of the light. The active area of the second photovoltaic cell issmaller than the light acceptance area defined by the array of opticalconcentrating elements by a concentration factor.

The first photovoltaic cell has an upper surface, a lower surface, andan array of optical passages therein in optical communication with theupper surface and the lower surface. In the context of the presentdisclosure, the expression “optical passages” should be understood asincluding any structure or combination of structures that allows lightto pass through that which the optical passage traverses, e.g. the firstphotovoltaic cell. No particular structure (other than that necessary toaccomplish the aforementioned function) is required. Non-limitingexamples of optical passages are openings, holes, light pipes, ortransparent materials that are appropriately structured and arrangedwith respect to the light in question. Thus, in the present disclosure,the expression an “array of optical passages therein in opticalcommunication with the upper surface and the lower surface” should beunderstood as any series of structures that allow light to pass from theupper surface of the first photovoltaic cell through the firstphotovoltaic cell and to exit from the lower surface of the firstphotovoltaic cell. The use of the word “array” in this context shouldnot be understood to require a particular ordering or grouping of theoptical passages or some portion of the optical passages. Further, eachof the optical passages in the array may be identical to the others,although they need not be.

The type, structure, method of manufacturing, and/or principle ofoperation of an optical passage may be a function of the type,structure, method of manufacturing and/or principle of operation of thefirst photovoltaic cell (although it may not be). In a non-limitingexample, in the case where the first photovoltaic cell is asingle-junction crystalline silicon flat-panel structure, the opticalpassages therein may be holes that have been laser drilled therein.

An array of optical concentrating elements is above the upper surface ofthe first photovoltaic cell defining a light acceptance area. In thecontext of the present disclosure, the expression “optical concentratingelement” should be understood as including any structure thatconcentrates light passing through it. Thus, non-limiting examples ofoptical concentrating elements include lenses, Fresnel lenses, Winstoncones, etc. It is not necessary that an optical concentrating elementconcentrate all of the light that passes through it. It is sufficientthat a majority of light passing through a structure be concentrated inorder for the structure to be considered an optical concentratingelement.

In some embodiments, optical concentrating elements serve the solefunction of concentrating the light impinging upon them. In otherembodiments, optical concentrating elements serve an additional functionwith respect to the light. As a non-limiting example, opticalconcentrating elements may also change the direction of the lightimpinging on them (e.g. focus the light). In some embodiments, some ofthe optical concentrating elements have the sole function ofconcentrating the light impinging on them, while other opticalconcentrating elements have an additional function(s) with respect tothe light. In some embodiments, the additional function(s) are the sameas between optical concentrating elements (that have an additionalfunction(s)), while in other embodiments, the additional function(s)differ between optical concentrating elements (that have an additionalfunction(s)).

The use of the word “array” in this context should not be understood torequire a particular ordering or grouping of the optical concentratingelements or some portion of the optical concentrating elements. In someembodiments, the optical concentrating elements of the array of opticalconcentrating elements are all of the same design. In other embodiments,various optical concentrating elements of the array of optical elementsare of different designs. The optical concentrating elements being“above the upper surface of the first photovoltaic cell”, includes bothstructures where the optical concentrating elements are in directphysical contact with the upper surface of the first photovoltaic celland those where the optical concentrating elements are not direct inphysical contact with the upper surface of the first photovoltaic cell(e.g. structures wherein the optical concentrating elements are spacedapart from the upper surface of the first photovoltaic cell).

The array of optical concentrating elements defines a “light acceptancearea” of the device. In this respect, each of the optical concentratingelements has a certain cross-sectional area (in a plane normal to theincoming direct light) through which the incoming light can enter thatoptical concentrating element. The totality of these areas of each ofthe optical concentrating elements is the light acceptance area of thearray.

Each of the optical concentrating elements is associated with one of theoptical passages. Thus, an optical concentrating element may beassociated with a single one of the optical passages. In such a case,all of the light from that optical concentrating element that enters anoptical passage enters a single optical passage (although it may be someof the light from that one of the optical concentrating elements entersno optical passage at all). Alternatively, an optical concentratingelement may be associated with more than one of the optical passages. Insuch a case, the light from that optical concentrating element thatenters an optical passage enters more than one optical passage(although, again, it may be that some of the light from that one of theoptical concentrating elements enters no optical passage at all). Thus,in some embodiments, each of the optical concentrating elements isassociated with a single optical passage. In other embodiments, each ofthe optical concentrating elements is associated with multiple opticalpassages. In still other embodiments, some of the optical concentratingelements are associated within a single optical passage while others ofthe optical concentrating elements are associated with multiple opticalpassages.

Each of the optical concentrating elements is structured and arranged toconcentrate direct light from the light source impinging on that opticalconcentrating element towards the one(s) of the optical passagesassociated with that optical concentrating element. It is not required,however, that all of the direct light from the light source impinging onthat optical concentrating element enter an optical passage; some ofsuch direct light may not enter an optical passage at all. Nor is itrequired that only direct light from the light source enter an opticalpassage; diffuse light may enter an optical passage as well. Noparticular structure or arrangement of an optical concentrating element(other than that necessary to accomplish the aforementioned function) isnecessary in the context of the present technology. In some embodiments,all of the optical concentrating elements are structured and/or arrangedin the same fashion. In other embodiments, the structure and/orarrangement of the various optical concentrating elements of a devicediffer.

In some embodiments the optical concentrating elements are lenses (thatare appropriately sized, shaped, structured, and arranged to carry outtheir required function). In some such embodiments, the lenses areformed in a first single layer of material (as opposed to being discreteindividual physical objects).

In some embodiments, each concentrating element is a circular lens (whenviewed from above). In some such embodiments, the circular lenses arearranged in a first pattern (when viewed from above) including a seriesof concentric circles having a first common center (i.e. the circularlenses are themselves arranged in a series of concentric circles). Insome such embodiments, for a given one of the series of concentriccircles, each of the lenses of that particular one of the series ofconcentric circles are of a same surface area (i.e., when viewed fromabove each of the lenses in that particular circle of lenses has thesame surface area as each of the other lenses in that particular circleof lenses). In some such embodiments, the common surface area of each ofthe lenses in a particular circle of lenses increases for each circle oflenses as one progresses away from the common center of all of thecircles of lenses.

In some embodiments, the lenses (be they circular lenses or otherwise,and whatever their surface area or construction might be) are arrangedin a hexagonal array (pattern). In other embodiments, the lenses (bethey circular or otherwise, and whatever their surface or constructionarea may be) are arranged in a Cartesian array (pattern). In still otherembodiments, the lenses (be they circular lenses or otherwise, andwhatever their surface area or construction might be) are arranged in anon-regularly-spaced algorithmically-determined array (i.e. the lensesare not randomly placed).

In some embodiments, the optical passages are openings right through thefirst photovoltaic cell. In some embodiments, where at least some of theconcentrating elements are (or include) lenses, a lens has a focal pointlocated with respect to its respective optical passage such that directlight concentrated by that lens passes through its respective opening inthe first photovoltaic cell. Between different embodiments the actuallocation of the focal point with respect to the opening will vary, forexample depending on the focal angle and focal length of the lens, thethickness of the first photovoltaic cell, and the size of the opening,in that particular embodiment. The focal point can be located withrespect to the opening at any location in which the passage of lightthrough the opening is not materially impeded. Thus, in some embodimentsthe focal point is centered between the entrance to and the exit fromthe opening. In other embodiments, the focal point is within the openingeither closer to the entrance or closer to the exit thereof. In stillother embodiments, the focal point is not within the opening but isclose to either the entrance or the exit thereof.

The concentrated direct light passes through the first photovoltaic cellvia the optical passage and exits the first photovoltaic cell via thelower surface. It is not necessary, however, that all of the lightentering an optical passage exit the first photovoltaic cell via thelower surface, or indeed exit the photovoltaic cell at all. In someembodiments, some of the light entering an optical passage may beabsorbed by the first photovoltaic cell. In some embodiments, some ofthe light entering an optical passage may exit the first photovoltaiccell other than via the lower surface. (In a non-limiting example, lightentering the optical passage may be reflected back and exit the firstphotovoltaic cell via the upper surface.) It is only necessary that atleast some of the light entering an optical passage exit the firstphotovoltaic cell via the lower surface; although in many embodiments,the device is structured to attempt to maximize the amount of lightexiting the first photovoltaic cell via the lower surface. It is notnecessary that light be identically treated by each optical passage; thetreatment and/or resultant fate of light entering different opticalpassages may differ.

Light exits via the lower surface of the first photovoltaic cell as anon-parallel beam. This does not require that all of the light raysexiting in a beam be non-parallel, only that the majority of raysexiting at any one time be non-parallel. Thus, in some embodiments, thelight rays in an exiting beam will be partially or entirely divergent.In other embodiments, the light rays in an exiting beam will bepartially or entirely convergent. In still other embodiments, the lightrays in an exiting beam will be a mixture of (at least) convergent anddivergent. In some embodiments, the light rays in a beam exiting thelower surface of the first photovoltaic cell are in a similar pattern aswith other exiting beams. In other embodiments, the light rays in thebeams exiting the lower surface of the first photovoltaic cell will bein a different pattern as between (at least some) different exitingbeams.

There is an array of optical redirecting elements below the lowersurface of the first photovoltaic cell. In the context of the presentdisclosure, the expression “optical redirecting element” should beunderstood as including any structure that changes the direction oflight impinging upon it. Thus, non-limiting examples of opticalredirecting elements include mirrored surfaces, surfaces that reflectlight via total internal reflection, etc. It is not necessary that anoptical redirecting element change the direction of all of the lightrays that impinge upon it. It is sufficient that a majority of the lightrays impinging upon a structure change their direction of travel inorder for the structure to be considered an optical redirecting element.

In some embodiments, optical redirecting elements serve the solefunction of redirecting the light impinging upon them. In otherembodiments, optical redirecting elements serve an additional functionwith respect to the light. As a non-limiting example, opticalredirecting elements may also concentrate the light impinging on them.In some embodiments, some of the optical redirecting elements have thesole function of changing the direction of light impinging on them,while other optical redirecting elements have an additional function(s)with respect to the light. In some embodiments, the additionalfunction(s) are the same as between optical redirecting elements (thathave an additional function(s)), while in other embodiments, theadditional function(s) differ between optical redirecting elements (thathave an additional function(s)).

Again, the use of the word “array” in this context should not beunderstood to require a particular ordering or grouping of the opticalredirecting elements or some portion of the optical redirectingelements. In some embodiments, the optical redirecting elements of thearray of optical redirecting elements are all of the same design. Inother embodiments, various optical redirecting elements of the array ofoptical elements are of different designs. The optical redirectingelements being “below the lower surface of the first photovoltaic cell”includes both structures wherein the optical redirecting elements are indirect physical contact with the lower surface of the first photovoltaiccell and those wherein the optical redirecting elements are not directin physical contact with the lower surface of the first photovoltaiccell.

Each of the optical redirecting elements is associated with one of theoptical passages. Thus, an optical redirecting element may be associatedwith a single one of the optical passages. In such a case, all of thelight that that optical redirecting element receives via an opticalpassage is received from a single optical passage (although it may bethat some of the light that that optical redirecting element receives isreceived other than via an optical passage). Alternatively, an opticalredirecting element may be associated with more than one of the opticalpassages. In such a case, the light that that optical redirectingelement receives via an optical passage is received from more than oneoptical passage (although, again, it may be that some of the light thatthat optical redirecting element receives is received other than via anoptical passage). In some embodiments, each of the optical redirectingelements is associated with a single optical passage. In otherembodiments, each of the optical redirecting elements is associated withmultiple optical passages. In still other embodiments, some of theoptical redirecting elements are associated within a single opticalpassage while others of the optical redirecting elements are associatedwith multiple optical passages.

Each of the redirecting elements receives the beam of light from theoptical passage with which that redirecting element is associated andredirects the beam of light optically towards a second photovoltaic cellfor harvesting thereby. Each of the optical redirecting elements isstructured and arranged to accomplish this function, however, noparticular structure or arrangement of an optical redirecting element(other than that which accomplishes the aforementioned function) isnecessary in the context of the present technology. In some embodiments,all of the optical redirecting elements are structured and/or arrangedin the same fashion. In other embodiments, the structure of and/orarrangement of (at least some of) the various redirecting elements of adevice differ.

It is not required that all of the light exiting the first photovoltaiccell via the lower surface thereof be redirected by a redirectingelement; some of such light may not be redirected. Nor is it requiredthat only light exiting the first photovoltaic cell via the lower thesurface be the only light redirected by a redirecting element; aredirecting element may also redirect (or otherwise affect) other lightas well.

In some embodiments, the optical redirecting elements are reflectors andredirecting the beam of light occurs via total internal reflection. Insome such embodiments, the reflectors each have a shape including aportion of a quadratic surface (e.g. paraboloidal, hyperboloidal,ellipsoidal, etc.). In some such embodiments, the reflectors both changethe direction of and concentrate the light beams. In such embodiments,it is not required that each of the reflectors be of the same shape(although they may be). In some embodiments, the reflectors are formedin a second single layer of material (as opposed to being discreteindividual physical objects).

In some embodiments, the redirecting elements redirect the beams oflight directly towards the second photovoltaic cell. (I.e. there is nofurther optically active element that materially changes the directionof travel of the light having been redirected by an optical redirectingelement towards the second photovoltaic cell prior to the lightimpinging upon the second photovoltaic cell.) In some such embodiments,the optical redirecting elements are shaped and arranged (one withrespect to each other and with respect to other optically activeelements of the device) such that at least 75% of each beam of light hasan unobstructed path from the optical redirecting element associatedtherewith to the second photovoltaic cell. In some such embodiments, theoptical redirecting elements are shaped and arranged such that each beamof light has an unobstructed path from the optical redirecting elementassociated therewith to the second photovoltaic cell.

In some embodiments, the optical redirecting elements are arranged in asecond pattern (when viewed from below) including a second series ofconcentric circles having a second common center (i.e. the opticalredirecting elements are themselves arranged in a series of concentriccircles).

In some embodiments, the optical redirecting elements are arranged in anarray (pattern) similar to that of the lenses.

The second photovoltaic cell is distinct from the first photovoltaiccell. The second photovoltaic cell has an active area receiving thebeams of the light; i.e., those that have been concentrated by theoptical concentrating elements, traversed the first photovoltaic cellvia an optical passage, and been redirected by the optical redirectingelements. (In some embodiments, the second photovoltaic cell may alsoharvest light other than the aforementioned beams of light.) The activearea of the second photovoltaic cell is smaller than the lightacceptance area defined by the array of optical concentrating elementsby a concentration factor. The concentration factor is any rationalnumber greater than 1; the concentrator factor need not be a wholenumber. The concentration factor can be determined by dividing the lightacceptance area defined by the array of optical concentrating elementsby the active area of the second photovoltaic cell associated with thatarray of optical concentrating elements. No particular concentrationfactor is required in the context of the present technology.

Diffuse light from the light source passes through the array of opticalconcentrating elements to the upper surface of the first photovoltaiccell and enters the first photovoltaic cell for harvesting thereby. Itis not required, however, that all of the diffuse light impinging on thedevice enter the first photovoltaic cell. As was discussed above, insome embodiments, some of the diffuse light enters an optical passage inthe first photovoltaic cell. In some embodiments, some of the diffuselight reflects off the upper surface of the first photovoltaic cell. Insome embodiments, some of the diffuse light is prevented from reachingthe upper surface of the first photovoltaic cell by some other structureof the device.

In some embodiments, environmental albedo light (e.g. diffuse light fromthe light source having been reflected off a surface behind thedevice—usually the ground) enters the lower surface of the firstphotovoltaic cell for harvesting thereby.

It is not required that diffuse light remain untreated by any opticalelement prior to its entry into the first photovoltaic cell (althoughthis is indeed the case in some embodiments). In some embodiments, forexample, some (or all) diffuse light may be treated by an opticalelement or system of elements (which can include, for example, theoptical concentrating elements described above, or otherwise) prior toits entry into the first photovoltaic cell.

It is not required that all of the diffuse light entering the firstphotovoltaic cell actually be harvested by the first photovoltaic cell.For example, photovoltaic cells are commonly not 100% efficient atharvesting the light that enters them.

It can thus be seen that via use of the present technology, direct lightand diffuse light impinging on the device are generally harvested bydifferent photovoltaic cells, the second photovoltaic cell and the firstphotovoltaic cell, respectively. In some embodiments, the secondphotovoltaic cell is a multiple-junction photovoltaic cell, e.g. a highefficiency cell. In some embodiments, the first photovoltaic cell is asingle-junction photovoltaic cell. In some embodiments, the secondphotovoltaic cell is a single photovoltaic cell. In other embodiments,the second photovoltaic cell is multiple photovoltaic cells (which maybe in direct physical contact with one another, spaced apart from oneanother, or some combination thereof.)

In some embodiments, the second photovoltaic cell has an upper surfaceand a lower surface (which are defined consistently with the uppersurface and the lower surface of the first photovoltaic cell). The beamsof light (directly or indirectly) from the array of optical redirectingelements enter the second photovoltaic cell through the lower surfacethereof (i.e. generally opposite from the direction which the diffuselight generally enters the first photovoltaic cell). In someembodiments, the beams of light enter the second photovoltaic cell onlythrough the lower surface thereof. In some such embodiments, the uppersurface of the second photovoltaic cell is adjacent the lower surface ofthe first photovoltaic cell (i.e. the two are “back to back”).

In other embodiments, the second photovoltaic cell is vertically spacedapart from the first photovoltaic cell, such that there is a gap betweenthem. In some such embodiments, the beams of light (directly orindirectly) from the array of optical redirecting elements enter thesecond photovoltaic cell through the upper surface thereof. In some suchembodiments the beams of light enter the second photovoltaic cell onlythrough the upper surface thereof. In other such embodiments the beamsof light enter the second photovoltaic cell through both the uppersurface and the lower surface thereof.

In some embodiments, the device further comprises an optical collectingelement. In the context of the present disclosure, the expression“optical collecting element” should be understood as any structure thatreceives light from more than one optical source element (of whateverkind) and redirects at least some of the received light to a commonoptical destination element (of whatever kind). Thus, non-limitingexamples of optical collecting elements include appropriately shaped,structured and arranged mirrored surfaces, surfaces that reflect lightvia total internal reflection, etc. An optical collecting element isstructured and arranged to accomplish the aforementioned function,however, no particular structure or arrangement (other than that whichaccomplishes the aforementioned function) is necessary in the context ofthe present technology. It is not required in the context of the presenttechnology that an optical collecting element be a single physicalstructure. Multiple or compound structures that accomplish theaforementioned function can, in some embodiments, be considered a singleoptical collecting element.

It is not necessary that an optical collecting element redirect all ofthe light received by it to a common optical destination element. It issufficient that at least some light from at least more than onedifferent optical source element is redirected to a common opticaldestination element in order for the structure to be considered anoptical collecting element. It is not necessary that an opticalcollecting element redirect light received by it to a single commonoptical destination element. In some embodiments (in a non-limitingexample, such as those wherein the second photovoltaic cell is multiplephotovoltaic cells) an optical redirecting element redirects lightreceived by it from multiple optical source elements to multiple commonoptical destination elements.

In some embodiments, an optical collecting element serves the solefunction of receiving and redirecting light as described herein above.In other embodiments, an optical collecting element serves an additionalfunction with respect to the light (whatever that function may be).

In some embodiments, a device of the present technology has more thanone optical collecting element. In such cases, in some embodiments, allof the optical collecting elements are structured and/or arranged in thesame fashion. In other embodiments, the structure and/or arrangement ofthe various optical collecting elements of a device differ.

The optical collecting element receives the beams of the light from thearray of optical redirecting elements and reorients (e.g. changes thedirection of) the beams of light optically towards the secondphotovoltaic cell. In the context of the present disclosure, “opticallytowards the second photovoltaic cell” should be understood as theoptical collecting element redirecting the light downstream to the nextoptically active element in the light's optical path towards the secondphotovoltaic cell, irrespective of the relationship of that optical pathto the actual physical location of the second photovoltaic cell. It isnot required that the optical collecting element reorient all of thelight that it receives; it is sufficient that the optical collectingelement reorient the majority of the light that it receives.

Thus, in some embodiments, the optical collecting element reorients thebeams of light directly towards the second photovoltaic cell (i.e. thereis no further optically active element that materially changes thedirection of travel of the light having been reoriented by the opticalcollecting element towards the second photovoltaic cell prior to thelight impinging upon the second photovoltaic cell).

In some embodiments, the optical redirecting elements are shaped andarranged (one with respect to each other and with respect to otheroptically active elements of the device) such that at least 75% of theeach beam of light (having been redirected by an optical redirectingelement) has an unobstructed path from the optical redirecting elementassociated with that beam of light to the optical collecting element. Insome such embodiments, the optical redirecting elements are shaped andarranged such that each beam of light has an unobstructed path from theoptical redirecting element associated therewith to the opticalcollecting element.

In some embodiments, the optical collecting element has a revolvedreflective surface including a portion of a quadratic surface (e.g.paraboloidal, hyperboloidal, ellipsoidal, etc.) in cross-section. Insome such embodiments, the optical collecting element both changes thedirection of and concentrates the light impinging upon it. In someembodiments, the revolved reflective surface is formed in a third singlelayer of material (as opposed to being formed of discrete individualphysical objects). In some embodiments, an axis of revolution of therevolved reflective surface passes through the first common center (ofthe lenses when arranged in the first series of centric circles) and thesecond common center (of the optical redirecting elements when arrangedin the second series of centric circles). In some embodiments, the axisof revolution of the revolved reflective surface passes through thesecond photovoltaic cell.

It should be understood, however, that the present technology does notrequire the presence of an optical collecting element.

In some embodiments, the second photovoltaic cell is in thermalcommunication with the first photovoltaic cell, and the firstphotovoltaic cell is the primary heat sink of the second photovoltaiccell; i.e., the majority of the heat from the second photovoltaic celltransferred away from the second photovoltaic cell by conduction istransferred to the first photovoltaic cell.

In some embodiments, the second photovoltaic cell is in thermalcommunication and electrical communication with an electric circuitsandwiched within the device. The electric circuit is the primary heatsink of the second photovoltaic cell; i.e. the majority of the heat fromthe second photovoltaic cell transferred away from the secondphotovoltaic cell by conduction is transferred to the electrical circuitsandwiched within the device.

In the context of the present specification, the words “first”,“second”, “third”, etc. have been used as adjectives only for thepurpose of allowing for distinction between the nouns that they modifyfrom one another, and not for the purpose of describing any particularrelationship between those nouns. Thus, for example, it should beunderstood that, the use of the terms “first” device and “third” deviceis not intended to imply any particular order, type, chronology,hierarchy or ranking (for example) of/between the devices, nor is theiruse (by itself) intended imply that any “second” device must necessarilyexist in any given situation. Further, as is discussed herein in othercontexts, reference to a “first” element and a “second” element does notpreclude the two elements from being the same actual real-world element.Thus, for example, in some instances, a “first” device and a “second”device may be the same device, in other cases they may be differentdevices.

Embodiments of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects and advantages ofembodiments of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, as well as otheraspects and further features thereof, reference is made to the followingdetailed description of certain embodiments which is to be used inconjunction with the accompanying drawings, where:

FIG. 1 is a perspective view of a solar panel assembly being a firstembodiment of the present technology.

FIG. 2 is a perspective view the solar panel assembly of FIG. 1 with theoptical concentrating units removed.

FIG. 3 is a close-up perspective view of one of the single-junctionphotovoltaic assemblies of the solar panel assembly of FIG. 1 along withoptical concentrating units and optical redirecting/collecting units.

FIG. 4 is an exploded perspective view of one of the single junctionphotovoltaic assemblies of the solar panel assembly of FIG. 1 along withoptical concentrating units and optical redirecting/collecting units.

FIG. 5 is a cross-section of the solar panel assembly of FIG. 1 takenalong the line 5-5 in FIG. 3.

FIG. 5A is a schematic view showing the path of light taken through aportion of the solar panel assembly of FIG. 1.

FIG. 5B is the same as FIG. 5, but without most reference numerals, forclarity.

FIG. 6 is a bottom plan view of the electrical conductor and portions ofthe electrical insulator of the solar panel assembly of FIG. 1.

FIG. 7 is a close-up view focused on a multiple-junction photovoltaiccell as indicated in FIG. 6.

FIG. 8 is a top plan view of the solar panel assembly of FIG. 1 asillustrated in FIG. 3.

FIG. 9 is a three-dimensional perspective cross-section view of aportion of a solar panel assembly being a second embodiment of thepresent technology.

FIG. 10 is a close-up three-dimensional perspective cross-section viewof the portion of the solar panel assembly of FIG. 9.

FIG. 11 is a schematic view of a portion of the solar panel assembly ofFIG. 9.

FIG. 11A shows the path light rays take through the assembly of FIG. 11.

FIG. 12 is a schematic view of a portion of the solar panel assembly ofFIG. 9.

FIG. 12A shows the path light rays take through the assembly of FIG. 12.

FIG. 13 is a schematic view of a portion of the solar panel assembly ofFIG. 9.

FIG. 13A shows the path light rays take through the assembly of FIG. 13.

FIG. 14 is a schematic view of a portion of the solar panel assembly ofFIG. 9.

FIG. 14A shows the path light rays take through the assembly of FIG. 14.

FIG. 15 is a schematic view of a portion of the solar panel assembly ofFIG. 9.

FIG. 16 is a cross-sectional schematic view of a portion of a solarpanel assembly being a third embodiment of the present technology.

FIG. 17 is a cross-sectional schematic view of a portion of a solarpanel assembly being a fourth embodiment of the present technology.

FIG. 18 is a cross-sectional schematic view of a portion of a solarpanel assembly being a fifth embodiment of the present technology.

FIG. 19 is a cross-sectional schematic view of a portion of a solarpanel assembly being a sixth embodiment of the present technology.

FIG. 20 is a cross-sectional schematic view of a portion of a solarpanel assembly being a seventh embodiment of the present technology.

FIG. 21 is a schematic view of a lens array.

FIG. 22 is a schematic view of a lens array.

FIG. 23 is a schematic view of a lens array.

FIG. 24 is a schematic perspective view of a solar panel assemblyillustrating a lens array.

FIG. 25 is a plan view of an embodiment of an electrical conductor.

FIG. 25A is a close-up plan view of the electrical conductor of FIG. 25.

FIG. 26 is a plan view of an embodiment of an electrical conductor.

FIG. 26A is a close-up plan view of the electrical conductor of FIG. 26.

In the figures there are a shown various solar panel assembliesincluding various embodiments of the present of the technology. It is tobe expressly understood that the various solar panel assemblies shown inthe figures are merely some exemplary embodiments of the presenttechnology. These are not, however, the only embodiments of the presenttechnology. Thus, the description that follows is intended to be only adescription of illustrative examples of the present technology. Thisdescription is not intended to define the scope or set forth the boundsof the present technology.

In some cases, what are believed to be helpful examples of modificationsto certain solar panel assemblies being embodiments of the presenttechnology may also be set forth in the description below. This is donemerely as an aid to understanding, and, again, not to define the scopeor set forth the bounds of the present technology. Where set forth,these modifications are not intended to be an exhaustive list, and, as aperson skilled in the art would understand, other modifications arelikely possible. Further, where this has not been done (i.e. where noexamples of modifications have been set forth), it should not beinterpreted that no modifications are possible and/or that what isdescribed is the sole manner of embodying that element of the presenttechnology. As a person skilled in the art would understand, this islikely not the case.

In addition it is to be understood that the solar panel assembliesdescribed below may provide in certain instances simple or simplifiedembodiments of the present technology, and that where such is the casethey have been presented in this manner as an aid to understanding. Aspersons skilled in the art would understand, various embodiments of thepresent technology will be of a greater complexity.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS First Embodiment (Overview)

Referring to FIG. 1, there is shown a perspective view solar panelassembly 100 for harvesting both direct and indirect sunlight, being anembodiment of the present technology. The solar panel assembly 100 is a“hybrid” solar panel assembly in that it has a concentrated photovoltaicaspect and a non-concentrated photovoltaic aspect. The solar panelassembly 100 has an upper surface 101 upon which sunlight to beharvested by the solar panel assembly 100 impinges, and enters the solarpanel assembly 100. The upper surface 101 has a plurality of opticalconcentrating units 104. Each of the optical concentrating units 104 hasan array of lenses 106 (not labelled in FIG. 1) that are structured andarranged to concentrate direct sunlight impinging on that lens 106.These optical concentrating units 104 are described in further detailbelow. A frame 108 surrounds the solar panel assembly 100 providingstructural integrity and edge protection to the solar panel assembly100. The dimensions of the solar panel assembly 100 are 1650 mm(length)×500 mm (width)×12 mm (depth). In this embodiment, thedimensions of the solar panel assembly 100 are slightly larger than thetotal of the dimensions of the all of the optical concentrating units104 because of small spaces between the units 104 and the presence ofthe frame. In other embodiments the dimensions of the solar panelassembly 104 differ, with no particular dimensions being required in thecontext of the present technology.

FIG. 2 shows the solar panel assembly 100 of FIG. 1 with the opticalconcentrating units 104 removed (for illustrative purposes). Below theoptical concentrating units 104 is a layer 110 comprised of a pluralityof flat-panel single-junction crystalline silicon photovoltaic cellassemblies 112 a, 112 b, 112 c etc. Diffuse sunlight impinging on anoptical concentrating unit 104 generally passes through that opticalconcentrating unit 104 to the single-junction photovoltaic cell assembly112 below for harvesting.

FIG. 3 shows a close-up perspective view of one of the single-junctionphotovoltaic cell assemblies 112 along with four optical concentratingunits 104 a, 104 b, 104 c, 104 d and two optical redirecting/collectingunit assemblies 114 a, 114 d of the solar panel assembly 100. In thisembodiment, each of the single-junction photovoltaic cell assemblies 112has the following dimensions: 150 mm (length)×150 mm (width)×0.2 mm(depth). In this embodiment each of the optical concentrating units 104has the following dimensions: 37.5 mm (length)×37.5 mm (width)×3 mm(depth). Thus, FIG. 3 shows the relative size relationship between anoptical concentrating unit 104 and a single junction photovoltaic cellassembly 112 in this embodiment. In this embodiment, eachsingle-junction photovoltaic cell assembly 112 is associated withsixteen optical concentrating units 104. In other embodiments, the sizesand shapes of the single-junction photovoltaic cell assembly 112 and/orthe optical concentrating units 104 (where they are present in thatembodiment) will vary, as will the ratio of the latter to the former. Noparticular such size, shape or ratio is required in the context of thepresent technology.

As is also shown in FIG. 3, below the bottom surface (unlabeled) of thesingle-junction photovoltaic cell assembly 112, on the bottom surface160 of the solar panel assembly 100, is a plurality of opticalredirecting/collecting unit assemblies 114. One opticalredirecting/collecting unit 114 d is shown as a part of the solar panelassembly 100 and another 114 a is shown in an exploded view apart fromthe solar panel assembly 100. As can be seen in the exploded view, inthis embodiment an optical redirecting/collecting unit assembly 114(e.g. 114 a) has an optical redirecting unit 116 (e.g. 116 a) and anoptical collecting unit 118 (e.g. 118 a) (which in use are matedtogether). Both the optical redirecting units 116 and the opticalcollecting units 118 are described in further detail below.

FIG. 3 also shows the relative size relationship between an opticalredirecting/collecting unit assembly 114, an optical concentrating unit104, and a single junction photovoltaic assembly 112. As can be seen inFIG. 3, in this embodiment, the optical redirecting/collecting unitassemblies 114 are the same size as the optical concentrating units.Thus, each of the optical redirecting/collecting units 114 also has thefollowing dimensions in this embodiment: 37.5 mm (length)×37.5 mm(width)×3 mm (depth). In this embodiment, each opticalredirecting/collecting unit assembly 114 is associated with one opticalconcentrating unit 104. Thus, each single junction photovoltaic cellassembly 112 is associated with sixteen optical redirecting/collectingunits 114. In other embodiments, the sizes and shapes of the opticalredirecting/collecting units 114, the single junction photovoltaic cellassembly 112 and/or the optical concentrating units 114 (where they arepresent in that embodiment) will vary, as will the ratio of any to theothers. No particular such sizes, shapes or ratios are required in thecontext of the present technology.

FIG. 4 shows an exploded perspective view of one of the single junctionphotovoltaic cell assemblies 112; along with one optical concentratingunit 104 and one optical redirecting/collecting unit 114 of the solarpanel assembly 100; while FIGS. 5 (and 5B) show a partial cross-sectionthereof. (FIG. 5B is identical to FIG. 5 with the exception that itshows fewer reference numerals for clarity. FIG. 5B will thus notseparately be referred to hereinbelow. All references to FIG. 5 hereininclude inherently a reference to FIG. 5B.) As can be seen in FIGS. 4and 5, starting from the upper surface 101 of the solar panel assembly100 and progressing to lower surface 160 of the solar panel assembly100, in this embodiment, the solar panel assembly 100 has the followingstructures:

(a) optical concentrating unit 104;

(b) bonding layer 120;

(c) upper structural layer 124;

(d) flat-panel crystalline silicon single-junction photovoltaic cell128;

(e) electrical insulator 130;

(f) electrical conductor 132;

(g) multiple-junction photovoltaic cell 134 (shown only in FIG. 5);

(h) encapsulation 136 (shown only in FIG. 5);

(i) lower structural layer 126;

(j) bonding layer 122;

(k) optical redirecting unit 116;

(l) optical collecting unit 118.

(A single junction photovoltaic cell assembly 112 of the solar panelassembly 100 includes (c) upper structural layer 124; (d) flat-panelcrystalline silicon single junction photovoltaic cell 128; (e)electrical insulator 130; (f) electrical conductor 132; (g)multiple-junction photovoltaic cell 134; (h) encapsulation 136 (shown inFIG. 5); and (i) lower structural layer 126. An opticalredirecting/collecting unit 114 of the solar panel assembly includes (k)optical redirecting unit 116 and (l) optical collecting unit 118.) Eachof these structures is described in further detail in turn below.

First Embodiment (Component Descriptions)

As was set forth above, in this embodiment, in the middle of the solarpanel assembly 100 there is a layer 110 comprised of a plurality offlat-panel single junction crystalline silicon photovoltaic cells 128.For purposes of economic efficiency, in this embodiment, thephotovoltaic cells 128 are conventional crystalline-silicon photovoltaiccells 128 such as those available from SunEdison™ of the USA, or MotechIndustries Inc. of Taiwan, or Yingli Solar of China.

In other embodiments, different photovoltaic cells 128 are used, someemploying the same technology as described above, others employingdifferent technology from that described above. For example, theconventional photovoltaic cells 128 from SunEdison™ etc. describedabove, are conventionally used to harvest both direct and indirectsunlight. In some embodiments of the present technology, however, littledirect sunlight is harvested via the photovoltaic cells 128 (as it ismostly harvested via the concentrated photovoltaic aspect of thedevice), therefore a single-junction crystalline silicon photovoltaiccell having been optimized for the purpose of generally harvestingdiffuse sunlight is employed. In this respect, for example, thephotovoltaic cell 128 could be optimized for better electrical energygeneration at the lower light energy levels and current densitiesinvolved. Such optimization could involve, for example, a change in thedoping and/or the metallization grid pattern (e.g. thinner bus bars 248and grid fingers 250—shown in FIG. 3—as less electrical current wouldneed to be handled).

In other embodiments, different types of photovoltaic cells 128 areemployed, including, for example, one of the following: triple junctioncrystalline silicon photovoltaic cells, heterojunction photovoltaiccells, copper-indium-gallium-selenide (CIGS) photovoltaic cells, singlelayer thin film photovoltaic cells, multi-layer thin film photovoltaiccells. As the purpose of these photovoltaic cells 128 is to harvestmostly diffuse light (and some direct light), any photovoltaic cellsuitable for this purpose employing any suitable technology could beused.

In this embodiment, the photovoltaic cells 128 have a plurality ofopenings 172 therein. (It should be understood that in the presentdescription, with a view to reducing complexity, where the contextwarrants, a reference number, e.g. 172, may be used generically to covervarious specificities, e.g. 172 a, 172 b, 172 c, etc.) The openings 172are circular in cross-section (in a plane normal to the direct sunlight144) and extend the entire depth of the photovoltaic cell 128, and thushave a 3D shape of a right circular cylinder, having a diameter of 0.3mm. The openings 172 are formed by laser drilling holes through thephotovoltaic cells 128 after their manufacture. In other embodiments,other suitable techniques, such as chemical etching or mechanicalmachining can be used to form the openings 172. The openings 172 aresized and arranged to allow focused direct light 148 to pass through thephotovoltaic cell 128 as is described in further detail below.

On the lower side (unlabelled) of the photovoltaic cell 128 is anelectrical insulator 130. In the present embodiment the electricalinsulator 130 is layer of aluminum oxide (Al₂O₃), having the followingdimensions: 150 mm (length)×150 mm (width)×0.1 mm (depth). In otherembodiments the electrical insulator 130 could be a layer of: silicondioxide (SiO₂), poly-methyl-methacrylate (PMMA),poly-tetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE),biaxially-oriented polyethylene terephthalate (BoPET—“Mylar”™), an airgap, etc. In still other embodiments the electrical insulator 130 couldbe any suitable material capable of serving as an electrical insulator(whether in layer form or otherwise) that is not otherwise incapable ofuse in a solar panel assembly 100. In some embodiments the electricalinsulator 130 could be a sheet of material having the same length andwidth as the solar panel assembly 100, while in other embodiments theelectrical insulator 130 can be a plurality of sheets to insulate eachindividual photovoltaic cell 128. In still other embodiments, theelectrical insulator 130 could be a material that is applied and allowedto cure directly in the solar panel assembly 100.

The primary purpose of the electrical insulator 130 is to electricallyinsulate the electrical conductor 132 (described in further detailbelow) from the photovoltaic cell 128. In other embodiments, theelectrical insulator 130 may have any other shape and/or dimensionsufficient to carry out its intended insulating purpose.

In this embodiment, the electrical insulator 130 has a series ofopenings 174 therein. The openings 174 are circular in cross-section (ina plane normal to the direct sunlight 144) and extend the entire depthof the electrical insulator 130, and thus have a 3D shape of a rightcircular cylinder, having a diameter of 0.3 mm. The openings 174 arealigned with the openings 172 of the photovoltaic cell 128, togetherforming, in this embodiment, a series of single right circular cylindersin 3D shape. In this embodiment, the openings 174 are formed by chemicaletching in the electrical insulator 130. In other embodiments, theelectrical insulator is transparent and no openings are present in theinsulator 130 as the focused direct light 148 simply passestherethrough.

On the lower side (unlabelled) of the electrical insulator 130, is anelectrical conductor 132. In the present embodiment, the electricalconductor 132 is formed of strips of copper (Cu) having the samedimensions as the photovoltaic cell 128. In other embodiments, theelectrical conductor 132 could be formed of strips of aluminum (Al),silver (Ag) or gold (Au), or an otherwise suitable alloy of any of theforegoing metals. In still other embodiments, the electrical conductor132 is any suitable material capable of serving as an electricalconductor (whether in strip form or otherwise) that is not otherwiseincapable of use in a solar panel assembly 100.

FIG. 6 shows a plan view of the electrical conductor 132 and portions ofthe electrical insulator 130. As can be seen in FIG. 6, the electricalconductor 132 is shaped to form two different current paths 162, 164 ofan electrical circuit (unlabeled) that includes the multiple-junctionphotovoltaic cells 134 associated with the photovoltaic cell 128. Theelectrical circuit has “positive” current path 162 connected to thepositive terminal (unlabelled) of each of the multiple-junctionphotovoltaic cells 134 and a “negative” current path connected to thenegative terminals 166 of each of the multiple junction photovoltaiccells 134 (see also FIG. 7 showing a close-up view of theseconnections).

The electrical conductor 132 has a series of openings 176 therein. Theopenings 176 are circular in cross-section (in a plane normal to thedirect sunlight 144) and extend the entire depth of the electricalconductor 132, and thus have a 3D shape of a right circular cylinder,having a diameter of 0.3 mm. The openings 176 are aligned with theopenings 174 of the electrical insulator; in this embodiment, togetherwith the openings 172, both forming a series of single right circularcylinders in 3D shape. In this embodiment, the openings 176 are formedby chemical etching in the electrical conductor 132.

While in the present embodiment each of the multiple-junctionphotovoltaic cells 134 associated with the single photovoltaic cell 128are connected together via a single electrical circuit, this is notrequired to be the case. In other embodiments, not all multiple-junctionphotovoltaic cells 134 or any particular grouping of multiple-junctionphotovoltaic cells 134 (e.g. those associated with a single photovoltaiccell 128) are connected together via a single electrical circuit. Inother embodiments, multiple electrical circuits (having separateelectrical paths) connect various multiple junction photovoltaic cells134. While in the present embodiment the electrical conductor 132 is inthe form of strips joined together to form the current paths 162, 164,this is not required to be the case. In other embodiments, theelectrical conductor 132 may have other shapes and dimensions sufficientto carry out its intended conducting purposes.

A series of passages 138 (138 a, 138 b, 138 c, 138 d, 138 e, 138 f—shownin FIG. 5) through the photovoltaic cell 128 (and the electricalinsulator 130 and the electrical conductor 132—as the case may be) areformed by the various aligned openings 172, 174, 176 therein (as thecase may be). In this embodiment, the passages 138 have the 3D shape ofa right circular cylinder. (In other embodiments, the passages 138 willhave different shapes, sizes, and/or lengths.) The passages 138 arefilled with the material forming the encapsulation 136, which isdescribed in further detail herein below. Referring to FIG. 5, in thisembodiment, passages 138 d, 138 e, 138 f are formed solely by openings172 d, 172 e, 172 f (respectively) in the photovoltaic cell 128 (therebeing no portion of the electrical insulator 130 nor any portion of theelectrical conductor 132 underneath the photovoltaic cell 128 in thevicinity of the openings 172 d, 172 e, 172 f). Passage 138 a is formedby opening 172 a in the photovoltaic cell 128 and by opening 174 a inthe electrical insulator 130 (openings 172 a and 174 a are aligned witheach other) (there being no portion of the electrical conductor 132underneath the electrical conductor 130 in the vicinity of the opening174 a). Passages 138 b, 138 c are formed by openings 172 b, 172 c(respectively) in the photovoltaic cell 128 and by openings 174 b, 174 c(respectively) in the electrical insulator 130 which are aligned withopenings 172 b, 172 c (respectively), and by openings 176 b, 176 c(respectively) in the electrical conductor 132 which are aligned withopenings 174 b, 174 c (respectively).

In this embodiment, multiple-junction photovoltaic cells 134 aremultiple-junction GaInP/GaInAs/Ge (III-V) photovoltaic cells having thefollowing overall dimensions: 1 mm (length)×1 mm (width). In otherembodiments, other multiple junction photovoltaic cells are used. Forexample, in some embodiments a multiple-junction photovoltaic cell of 2mm (length)×2 mm (width) may be employed, while in other embodiments amultiple-junction photovoltaic cell 3 mm (length)×3 mm (width) may beemployed.

In this embodiment, the electrical insulator 130, the electricalconductor 132, and the multiple-junction photovoltaic cells 134 areencapsulated in an encapsulation 136, for protective, structural, andinsulation purposes. Further, as was discussed above, the passages 138are completely filled with the material of the encapsulation 136.

In this embodiment, the encapsulation 136 is a polymerized siloxanematerial (e.g. silicone). In other embodiments, the encapsulation 136 isa carbon-based polymer (e.g., PMMA, PTFE, ETFE, BoPET, etc.), aninsulant (e.g. Al₂O₃), or a copolymer (e.g. EVA). In still otherembodiments, no encapsulation is present and the electrical insulator130, the electrical conductor 132, and the multiple junctionphotovoltaic cells 134 are in an air layer within the solar panelassembly. In still other embodiments, the encapsulation may be made ofthe same material and as a single component with the optical bondinglayer 120 (described in further detail below).

In this embodiment, the photovoltaic cell 128, the electrical insulator130, the electrical conductor 132, the multiple-junction photovoltaiccells 134, and the encapsulation 136 are sandwiched between twostructural layers, an upper structural layer 124 and a lower structurallayer 126. The structural layers 124, 126 serve to provide structure andrigidity to the solar panel assembly 100. In this embodiment, the bothof the structural layers 124, 126 are sheets of soda-lime-silica glass.The upper structural layer 124 having the following dimensions: 1.65 m(length)×0.5 m (width)×4 mm (depth). The lower structural layer 126having the following dimensions: 1.64 m (length)×0.49 m (width)×1.6 mm(depth). In this embodiment, the lower structural layer 126 is of asmaller depth for ease of assembly. In other embodiments, sheets ofother types of glass (e.g. vitreous silica glass, sodium borosilicateglass, lead-oxide glass, aluminosilicate glass, oxide glass, etc.) nototherwise incompatible with their use in a solar panel assembly areused. In still other embodiments, the structural layers 124, 126 couldbe made of any otherwise appropriate transparent polymer (in sheet formor otherwise suitable form). Although in this embodiment the structurallayers 124, 126 are made of the same material, this is not required. Inother embodiments the structural layers 124, 126 could be made ofdifferent materials. The structural layers 124, 126 in other embodimentsare of different dimensions. The structural layers 124, 126 need only beappropriately sized and dimensioned to carry out their intendedfunction.

In this embodiment, as was discussed above, there are sixteen opticalconcentrating units 104 above and bonded to the upper structural layer124 (the upper sheet of glass). As in this embodiment each of theoptical collecting units 104 are identical, only one will be discussed.(There is no requirement that the optical collecting units—wherepresent—be identical and in other embodiments the optical collectingunits present will differ.) In this embodiment, each opticalconcentrating unit 104 is made of transparent injection-molded PMMA. Inother embodiments, an optical concentrating unit 104 (where present) canbe made of any otherwise appropriate light-transmissive material.Non-limiting examples include poly-methyl-methacrylimide (PMMA),polycarbonates, cyclo-olefin-polymers (COP), cyclo-olefin-copolymers(COC), PTFE, glasses, etc. The method of manufacturing could vary(depending on the material); e.g. in some embodiments casting orembossing are used.

Referring to FIGS. 3, 5 and 8, in this embodiment, in the center of theupper surface 102 (along the central axis 168) of the optical collectingunit 104 (which in this embodiment forms the upper surface 101 of thesolar panel assembly 100) is a flat portion 170 which is intended to benormal to direct sunlight 144 when the solar panel 100 assembly is inuse. Vertically below this flat portion 170 is the multiple-junctionphotovoltaic cell 134. When viewed from above, the flat portion 170 isin the shape of a circle. Surrounding the flat portion 102 are lenses106. Lenses 106 are arranged in a series of circles 172 a, 172 b, 172 c,etc. (starting closest to the flat portion and moving outward) having acommon center (along the central axis 168), being the center of theoptical concentrating unit 104. In this embodiment, the lenses 106 ofthe circle 172 a closest to the flat portion 170 all have a commondiameter D_(a) (when viewed from above). The lenses 106 of the circle172 b immediately outward from the circle 172 a all have a commondiameter D_(b) that is greater than D_(a). The lenses 106 of the circle172 c immediately outward from the circle 172 b all have a commondiameter D_(c) that is greater than D_(b). This trend of increasingdiameters D_(x) continues as one progresses away from the flat portion170. Lenses 106 that meet the edge surface 246 of the opticalconcentrating unit 104 are “cut-off” by the edge surface 246 and areonly partial structures. The lower surface (unlabelled) of the opticalcollecting unit 104 is flat.

Referring to FIG. 5 each of the lenses 106 of the optical concentratingunit 104 is shaped to have a focal point 150 through the photovoltaiccell 128 (and electrical insulator 130 and electrical conductor 132—asthe case may be) at the exit of a passage 138 in the encapsulation 136.Further each lens 106 and its associated passage 138 are cooperativelyshaped and sized such that effectively all direct sunlight 144 impingingon the surface 146 of the lens 106 is focused towards the focal point150, and all of the focused light 148 enters and traverses the passage138 and arrives at the focal point 150. Thus, when the solar panelassembly 100 directly faces the sun, direct sunlight rays 144 a impingeon the surface 146 a of the lens 106 a and are focused by the lens 106 a(through the photovoltaic cell 128 and the electrical insulating layer130) at focal point 150 a, which is at the exit of passage 138 a in theencapsulation 136 material. The focused light rays 148 a traverse theremainder of the body of the lens 106 a, the optical bonding layer 120(described in further detail below), the upper structural layer 124,enter the passage 138 a filled with the encapsulation 136 material, andtraverse the photovoltaic cell 128 and the electrical insulating layer130 through the passage 138 a, and arrive at the focal point 150 a oflens 106 a. Similarly, direct sunlight rays 144 c impinge on the surface146 c of the lens 106 c and are focused by the lens 106 c (through thephotovoltaic cell 128, the electrical insulating layer 130, and theelectrical conducting layer 132) at focal point 150 c, which is at theexit of passage 138 c in the encapsulation 136 material. The focusedlight rays 148 c traverse the remainder of the body of the lens 106 c,the optical bonding layer 120, the upper structural layer 124, enter thepassage 138 c, and traverse the photovoltaic cell 128, the electricalinsulating layer 130, and the electrical conducting layer, through thepassage 138 c, and arrive at the focal point 150 c of lens 106 c.

In this embodiment, there is a transparent bonding layer 120 that bondsthe optical concentrating units 104 to the upper surface (unlabelled) ofthe upper structural layer 124. The bonding layer 120 is sufficientlyelastically deformable to accommodate shear stress developed as a resultof changes in temperature of the solar panel assembly 100 and thedifference (if any) between the coefficient of thermal expansion of thematerial of which the optical concentrating unit 104 is made and thecoefficient of thermal expansion of the material of which the upperstructural layer 124 is made. In this embodiment, the transparentbonding layer 120 is made of ethylene vinyl acetate (EVA). In otherembodiments, the transparent bonding layer (if present) could be made ofpolymerized siloxane (e.g. silicone), polyvinyl acetate (PVA), anyotherwise suitable ionomer, etc. (A note on thermal expansion: Thepassages 138 are sized and shaped such that they can accommodate a shiftin the focal point of their associated lenses 106 owing to thedifferences in the coefficients of thermal expansion referred to above.In addition, the multiple-junction photovoltaic cells 134 are of asufficient size such that minor changes to the light ray paths thatoccur because of the differences in the coefficients of thermalexpansion referred to above are accommodated. In this embodiment theoptical concentrating units 104 and the optical redirecting/collectingunits 114 are made of the same material. They therefore have the samecoefficients of thermal expansion and thus in most cases the alignmentbetween them will be very minimally affected, if at all.)

In this embodiment, as was discussed above there are sixteen opticalredirecting/collecting units 114 below and bonded to the lowerstructural layer (lower sheet of glass) 126. As in this embodiment eachof the optical redirecting/collecting units 114 are identical only onewill be discussed. (There is no requirement that the opticalredirecting/collecting units 114—where present—be identical and in otherembodiments the optical collecting units present will differ.) In thisembodiment, each optical redirecting/collecting unit 114 has twocomponents, an (upper) optical redirecting unit 116 and a (lower)optical collecting unit 118, each of which is a 37.5 cm square unit(when viewed from above) having a depth of 3 mm made of transparentinjection-molded PMMA. In other embodiments, an optical redirecting unit116 and an optical collecting unit 118 (where present) can be made ofany otherwise appropriate light-transmissive material. Non-limitingexamples include poly-methyl-methacrylimide (PMMA), polycarbonates,cyclo-olefin-polymers (COP), cyclo-olefin-copolymers (COC), PTFE,glasses, etc. The redirecting/collecting unit 114 has a depth of 6 mm.In this embodiment the redirecting units 116 and the optical collectingunits 118 are bonded together with an optical adhesive such as silicone.(Not shown in the figures.) In other embodiments, the redirecting units116 and the optical collecting units 118 may be injection molded as asingle piece to form the redirecting/collecting units 114. The method ofmanufacturing could vary (depending on the material); e.g. in someembodiments casting or embossing are used.

Referring to FIGS. 3, 4 and 5, in this embodiment, the upper surface(unlabelled) of the optical redirecting unit 116 is flat. The centralportion 180 of the lower surface 178 of the optical redirecting unit 116is flat (when viewed from the side) and is generally the same size andshape (e.g. a circle) as the central portion 170 of the upper surface102 of the optical concentrating unit 104 (when viewed from below).Extending from the central portion 180, the lower surface 178 has arotationally-symmetric (but for being cut off by the square-shaped edgesurfaces) downwardly-sloping planar portion 182 (i.e. forming thesurface of a right circular conical frustum in 3D). Extending upwardlyfrom the planar portion 182 of the lower surface 178 into the body 184is a series of crescent-shaped (when viewed from below) recesses 140.The recesses 140 c/140 d closest to the flat central portion 180 are thesmallest in both area and depth and the recesses 140 grow larger in botharea and depth the further they are from the central portion 180. Thearea of each recess 140 decreases along its depth progressing away fromthe lower surface 178. The edge surfaces 142 of each recess 140 thatface the central portion 180 is a portion of a circular paraboloid(whose particular shape is described below in further detail). The edgesurfaces 186 of each recess 140 opposite the paraboloidal-portionsurfaces 142 are a portion of an outer surface of right circularcylinder. In this embodiment, air fills each recess 140.

In this embodiment, the upper surface 188 of the optical collecting unit118 is generally complimentary to (with the exception of the recesses140) and registers with the lower surface 178 of the optical redirectingunit 116. Thus, the upper surface 188 of the optical collecting unit 118has a central flat portion 190 that is complimentary in size and shapeto the central flat portion 180 of the lower surface 178 of the opticalredirecting unit 116. Extending from the central portion 190, the uppersurface 188 has a rotationally-symmetric (but for being cut off by thesquare-shaped edge surfaces) downwardly-sloping planar portion 192 (i.e.forming the surface of a right circular conical frustum in 3D). Thedownwardly-sloping planar portion 192 of the upper surface 188 of theoptical collecting unit 118 is generally complimentary in size and shape(with the exception of the recesses 140) to the downwardly-slopingplanar portion 182 of the lower surface 178 of the optical redirectingunit 116. When the optical collecting unit 118 is mated with (and bondedto) the optical redirecting unit 116 to form opticalredirecting/collecting unit 114, the downwardly-sloping planar portion192 of the upper surface 188 of the optical collecting unit 118 closesthe recesses 140 in the downwardly-sloping planar portion 182 of thelower surface 178 of the optical redirecting unit 116 retaining the airin the recesses 140.

In this embodiment, the lower surface 194 of the optical collecting unit118 (which forms a part of the lower surface 160 of the solar panelassembly 100) has a flat (when viewed from the side) central portion196, which is smaller in size than the flat central portion 190 of theupper surface 188 of the optical collecting unit 118. Extending from thecentral portion 196, the lower surface 194 has a rotationally-symmetric(but for being cut off by the square-shaped edge surfaces)upwardly-facing curved portion 198. The curved portion 198 has the shapeof surface of revolution formed by revolving a section of a parabolaabout an axis, whose particular shape is described below in furtherdetail.

In this embodiment, there is a transparent bonding layer 122 that bondsthe optical redirecting units 116 to the lower surface (unlabelled) ofthe lower structural layer 126. The bonding layer 122 is sufficientlyelastically deformable to accommodate shear stress developed as a resultof changes in temperature of the solar panel assembly 100 and thedifference (if any) between the coefficient of thermal expansion of thematerial of which the optical redirecting unit 116 is made and thecoefficient of thermal expansion of the material of which the lowerstructural layer 126 is made. In this embodiment, the transparentbonding layer 122 is made of ethylene vinyl acetate (EVA). In otherembodiments, the transparent bonding layer (if present) is made ofpolymerized siloxane (e.g. silicone), polyvinyl acetate (PVA), anyotherwise suitable ionomer, etc. In this embodiment, bonding layer 122is made of the same material as bonding layer 120; however in otherembodiments bonding layer 122 is made of a different material thanbonding layer 120. The bonding layer 122 has the following dimensions1.65 m (length)×0.50 m (width)×400 μm (depth).

First Embodiment (Light Paths)

Referring to FIG. 5, once the focused light rays 148 arrive at andtraverse the focal point 150 of the lens 106, the light rays 152 beginto diverge as they travel away from the focal point 150. The diverginglight rays 152 traverse the remainder of the encapsulation 136, thelower structural layer 126, the bonding layer 122, and the body 184 ofthe optical redirecting unit 116. The divergent light rays 152 impingeupon the curved edge surface 142 of a recess 140. Curved edge surface142 acts as reflector that functions on the basis of total internalreflection owing to the difference between the refractive index of thePMMA of the body 184 of the optical redirecting element 116 and therefractive index of the air in the recess 140. The divergent light rays152 reflect off the curved edge surface 142 back into the body 184 ofthe optical redirecting unit 116 and are redirected (owning to the shapeof the curved edge surface 142) towards the curved portion 198 of thelower surface 194 of the optical collecting unit 118. The redirectedlight rays 154 traverse the body 184 of the optical redirecting unit 116and the body (unlabelled) of the optical collecting unit 118. Theredirected light rays 154 impinge upon the curved portion 198 of thelower surface 194 of the optical collecting unit 118. Curved portion 198acts as a reflector that functions on the basis of total internalreflection owing to the difference between the refractive index of thePMMA of the body of the optical collecting unit 118 and the refractiveindex of the ambient air below the lower surface 194 of the opticalcollecting unit 118. The redirected light rays 154 reflect off thecurved portion 198 back into the body of the optical collecting unit 118towards the multiple-junction photovoltaic cell 134 (as collected lightrays 156—owing to the shape of the curved portion 198). The collectedlight rays 156 traverse the body of the optical collecting unit 118, thebody 184 of the optical redirecting unit 116, the bonding layer 122, thelower structural layer 126, the encapsulation 136 and impinge upon themultiple-junction photovoltaic cell 134 for harvesting.

As was discussed above, in this embodiment, the curved edge surface 142of each recess 140 in the lower surface 178 of the optical redirectingelement 116 (which acts as a reflector) has the shape of an off-axisportion of a paraboloid. The curved portion 198 of the lower surface 194of the optical collecting element 118 (which also acts a reflector) hasthe shape of a section of a parabola rotated around an axis ofrevolution (collinear with the central axis 168) perpendicular to theaxis of the parabola used to create a surface of revolution. Each ofthese surfaces 142, 198 has its own particular position (within the unit116, 118 of which it is a part), shape and orientation such that thediverging focused direct light 152 follows an optical path from a focus150 to the multiple-junction photovoltaic cell 134 as was describedhereinabove.

Thus, continuing with the above example, in this embodiment, when thesolar panel assembly 100 directly faces the sun, direct sunlight rays144 a impinge on the surface 146 a of the lens 106 a and are focused bythe lens 106 a (through the photovoltaic cell 128 and the electricalinsulating layer 130) towards focal point 150 a, which is at the exit ofpassage 138 a. The focused light rays 148 a traverse the remainder ofthe body of the lens 106 a, the optical bonding layer 120, the upperstructural layer 124, enter the encapsulation 136 material within thepassage 138 a, and traverse the photovoltaic cell 128 and the electricalinsulating layer 130 through the passage 138 a, and arrive at the focalpoint 150 a of lens 106 a in the encapsulation 136. From the focal point150 a, the diverging focused light rays 152 a traverse the remainder ofthe encapsulation 136, the lower structural layer 126, the opticalbonding layer 122, and the body 184 of the optical directing element 116and impinge upon the curved edge surface 142 a of recess 140 a in thelower surface 178 of the optical redirecting unit 116. The curved edgesurface 142 a is positioned, sized, shaped and orientated such that thelight rays 152 a reflect off the curved edge surface 142 a in adirection parallel to the axis of the paraboloid defining shape of thecurved edge surface 142 a. (The axis of the paraboloid is not shown inFIG. 5 although it is generally parallel to the light rays 154 a shownreflecting off the curved edge surface 142 a. In this embodiment, thefocus of the paraboloid is designed to be coincident with the focus ofthe lens 150 a. As can be seen in FIG. 5, however, when the solarassembly 100 is in use, owing to several factors including thermalexpansion of the various components of the solar assembly 100, the focusof the paraboloid is very slightly off from the focus of the lens 106 a.This causes the light rays 154 a in FIG. 5 to appear to be slightlyconvergent. At other points in time in the solar panel assembly's 100use, the light rays 154 a might appear to be slightly divergent.)

The (now) redirected light rays 154 a traverse the body 184 of theoptical redirecting element 116 and the body of the optical collectingelement 118 and impinge on the curved portion 198 of the lower surface194 of the optical collecting element 118. The curved edge portion 198is positioned, shaped and orientated such that the light rays 154 areflect off curved portion 198 towards the focus of the paraboladefining the shape of the curved portion 198. In this embodiment, thefocus is not shown in FIG. 5 although it is above (and behind, relativeto the light path) the multiple-junction photovoltaic cell 134. In otherembodiments, the focus of the parabola defining the shape of the curvedportion 198 is located at the center of the bottom face or on the bottomface of the multiple-junction photovoltaic cell 134. The (now) collectedlight rays 156 a traverse the body of the optical collecting element118, the optical redirecting element 116, the bonding layer 122, thelower structural layer 126, the encapsulation 136 and impinge upon themultiple-junction photovoltaic cell 134, which the light rays 156 aenter for harvesting.

Similarly, in this embodiment, direct sunlight rays 144 c impinge on thesurface 146 c of the lens 106 c and are focused by the lens 106 c(through the photovoltaic cell 128, the electrical insulating layer 130and the electrical conducting layer 132) towards focal point 150 c,which is at the exit of passage 138 c. The focused light rays 148 ctraverse the remainder of the body of the lens 106 c, the opticalbonding layer 120, the upper structural layer 124, enter theencapsulation material within the passage 138 c, and traverse thephotovoltaic cell 128, the electrical insulating layer 130, and theelectrical conducting layer, through the passage 138 c, and arrive atthe focal point 150 c of lens 106 c in the encapsulation. From the focalpoint 150 c, the diverging focused light rays 152 c traverse theremainder of the encapsulation 136, the lower structural layer 126, theoptical bonding layer 122, and the body 184 of the optical directingelement 116 and impinge upon the curved edge surface 142 c of recess 140c in the lower surface 178 of the optical redirecting unit 116. Thecurved edge surface 142 c is positioned, sized, shaped and orientatedsuch that the light rays 152 c reflect off the curved edge surface 142 cparallel to the axis of the paraboloid defining the shape of the curvededge surface 142 c. (The axis of the paraboloid is not shown in FIG. 5although it is generally parallel to the light rays 154 c shownreflecting off the curved edge surface 142 c. In this embodiment, thefocus of the paraboloid is designed to be coincident with the focus ofthe lens 150 c. As can be seen in FIG. 5, however, when the solarassembly 100 is in use, owing to several factors including thermalexpansion of the various components of the solar assembly 100, the focusof the paraboloid is very slightly off from the focus of the lens 106 c.This causes the light rays 154 c in FIG. 5 to appear to be slightlydivergent. At other points in time in the solar panel assembly's 100use, the light rays 154 c might appear to be slightly convergent.)

The (now) redirected light rays 154 c traverse the body 184 of theoptical redirecting element 116 and the body of the optical collectingelement 118 and impinge on the curved portion 198 of the lower surface194 of the optical collecting element 118. The curved edge portion 198is positioned, sized, shaped and orientated such that the light rays 154c reflect off curved portion 198 towards the focus of the paraboladefining the shape of the curved portion 198. In this embodiment, thefocus is not shown in FIG. 5 although it is above (and behind, relativeto the light path) the multiple-junction photovoltaic cell 134. In otherembodiments, the focus of the parabola defining the shape of the curvedportion 198 is located at the center of the bottom face or on the bottomface of the multiple-junction photovoltaic cell 134. The (now) collectedlight rays 156 c traverse the body of the optical collecting element118, the optical redirecting element 116, the bonding layer 122, thelower structural layer 126, the encapsulation 136 and impinge upon themultiple-junction photovoltaic cell 134, which the light rays 156 center for harvesting. (The optical collecting unit 118 is termed a“collecting” unit as, in this embodiment, the light rays 154 that havebeen redirected by any of the reflectors formed by the curved edgesurfaces 142 of any of the recesses 140 are all reoriented towards themultiple junction photovoltaic cell 134 by the curved portion 198 of thelower surface 194 of the optical collecting unit 118, thus “collecting”thus light rays 154.)

Still referring to FIG. 5, in this embodiment, direct light rays 200that impinge upon the upper surface 102 of the solar panel assembly 100that do not impinge upon a lens 106 impinge upon the central flatportion 170 or a portion 214 between the lenses 106 of the upper surface102 of an optical concentrating unit 104. Because their angle ofincidence with the upper surface 102 is 90°, no refraction occurs(notwithstanding the difference between the index of refraction of theambient air above the upper surface 102 and the index of refraction ofthe PMMA of the optical concentrating unit 104). Thus, in thusembodiment, such direct light rays 200 continue straight through theupper surface 102 and traverse the optical concentrating unit 104, thebonding layer 120, the upper structural layer 124, and impinge upon thephotovoltaic cell 128 for harvesting. Thus, in the present embodiment,not all of the direct light rays impinging on the solar panel array 100are harvested via a multiple-junction photovoltaic cell 134; some directlight rays 200 are harvested via a single-junction photovoltaic cell128.

Still referring to FIG. 5, in this embodiment, diffuse light rays 202,206 that impinge upon the upper surface 102 of the optical concentratingunit 104 impinge either on the central flat portion 170 a, a portion 214between the lenses 106, or on one of the lens surfaces 146 of a lens106. Diffuse light rays 202 infringing upon the central flat portion 170a or a portion 214 are refracted upon entry into the body of the opticalconcentrating element 104 (owing to the difference between the index ofrefraction of the ambient air above the upper surface 102 and the indexof refraction of the PMMA of the optical concentrating unit 104).Resultant refracted light rays 204 traverse the optical concentratingunit 104, the boding layer 120, the upper layer structural 124, andimpinge upon the photovoltaic cell 128 for harvesting. Diffuse lightrays 206 infringing upon the surface 146 (e.g. 146 f) of a lens 106(e.g. 106 f) are also refracted upon entry into the body of the opticalconcentrating element 104 (owing to the difference between the index ofrefraction of the ambient air above the upper surface 102 and the indexof refraction of the PMMA of the optical concentrating unit 104).Resultant refracted light rays 208 traverse the optical concentratingunit 104, the boding layer 120, the upper layer structural 124, andimpinge upon the photovoltaic cell 128 for harvesting.

Still referring to FIG. 5, in this embodiment, the solar panel assembly100 is capable of harvesting some diffuse albedo light rays. In thisrespect, diffuse albedo light ray 210 has resulted from a light rayhaving been reflected off a background surface behind (underneath) thesolar panel assembly 100. Diffuse albedo light rays 210 impinge upon thecurved portion 198 of the lower surface 194 of the optical collectingunit 118. Diffuse albedo light rays 210 are refracted upon entry intothe body of the optical collecting unit element 118 (owing to thedifference between the index of refraction of the ambient air below thelower surface 194 and the index of refraction of the PMMA of the opticalcollecting unit 118). Resultant refracted light rays 212 traverse thebody of the optical collecting unit 118, and either solely the body 184of the optical redirecting element 116 or the body 184 of the opticalredirecting element 116 and the air pocket created by a recess 140 (asthe case may be), and the bonding layer 122, the lower structural layer126, the encapsulation 136 and then impinge on the photovoltaic cell 128for harvesting.

As a person skilled in the art would understand, FIG. 5 is not granularenough to show the refractive changes in the light paths as the lightrays progress from one material to another once inside the solar panelassembly 100. Those light paths appear in FIG. 5 to be straight lines asif the various components had the same refractive index, when inactuality the paths are not straight lines as the various componentshave different refractive indices (albeit in the same range). In thisrespect, the refractive index of PMMA is 1.49469626; the refractiveindex of silicone is 1.40654457; the refractive index of glass:1.51947188; and the refractive index of EVA is 1.49370420. Therefractive index of air is 1.00027

FIG. 5A is a schematic view of a portion of the light path of a directsunlight ray 144 a impinging on lens 106 a as described above. FIG. 5Aillustrates the effect of the difference in the refractive indices ofthe various components. The aforementioned example with direct light ray144 a will be used. Direct light ray 144 a is refracted at the lenssurface 146 a because of the difference between the refractive indicesof air (1.00027) and PMMA (1.49469626), and is focused toward the focalpoint 150 a of the lens 106 a. The angle of incidence 215 is 14.6945°.The focused refracted light ray 148 a in FIG. 5, (which is considered asa single linear light ray in that figure) is illustrated in FIG. 5A asseparate light rays 216, 220, 224, and 228, each of which are describedin turn.

Focused light ray 216 traverses the body of the optical concentratingunit 104 to the boundary 218 between the optical concentrating unit 104and the bonding layer 120. Light ray 216 is refracted at the boundary218 because of the difference between the refractive indices of PMMA(1.49469626) and EVA (1.49370420) as light ray 220. The effective angleof incidence 219 is 14.7074°. (The effective angle of incidence 219 isthe angle between the light ray 220 and a line 221 parallel to directlight ray 144 a.)

Light ray 220 traverses the bonding layer 120 to the boundary 222between the bonding layer 120 and the upper structural layer 124. Lightray 220 is refracted at the boundary 222 because of the differencebetween the refractive indices of EVA (1.49370420) and glass(1.51947188) as light ray 224. The effective angle of incidence 223 is14.4477°. (The effective angle of incidence 223 is the angle between thelight ray 224 and a line 225 parallel to direct light ray 144 a.)

Light ray 224 traverses the upper structural layer 124 to the boundary226 between the upper structural layer 124 and the encapsulation 136material within the passage 138 a. Light ray 224 is refracted at theboundary 226 because of the difference between the refractive indices ofglass (1.51947188) and silicone (1.40654457) as light ray 228. Theeffective angle of incidence 227 is 15.6097°. (The effective angle ofincidence 227 is the angle between the light ray 228 and a line 229parallel to direct light ray 144 a.) Light ray 228 traverses the passage138 and traverses the focal point 150 a of the lens 160 a. In FIG. 5, atthis point, the focused refracted light ray 148 a in FIG. 5 (which isconsidered as a single linear light ray in that figure) traverses thefocal point 150 a and leaves as light ray 152 a in FIG. 5 (which is alsoconsidered as a single linear light ray in that FIG. 5). FIG. 5A,however, is far more granular and light ray 228 traverses the focalpoint 150 a and is light ray 230.

Light ray 230 traverses the encapsulation 136 to the boundary 232between the encapsulation 136 and the lower structural layer 126. Lightray 220 is refracted at the boundary 232 because of the differencebetween the refractive indices of silicone (1.40654457) and glass(1.51947188) as light ray 234. The effective angle of incidence 231 is15.6045°. (The effective angle of incidence 231 is the angle between thelight ray 234 and a line 235 parallel to direct light ray 144 a.)

Light ray 234 traverses the lower structural layer 126 to the boundary236 between the lower structural layer 126 and bonding layer 122. Lightray 234 is refracted at the boundary 236 because of the differencebetween the refractive indices of glass (1.51947188) and EVA(1.49370420) as light ray 238. The effective angle of incidence 237 is14.1470°. (The effective angle of incidence 237 is the angle between thelight ray 238 and a line 239 parallel to direct light ray 144 a.)

Light ray 238 traverses bonding layer 122 to the boundary 240 betweenthe bonding layer 122 and the optical redirecting unit 116. Light ray238 is refracted at the boundary 240 because of the difference betweenthe refractive indices of EVA (1.49370420) and PMMA (1.49469626) aslight ray 242. The effective angle of incidence 237 is 14.6583°. (Theeffective angle of incidence 239 is the angle between the light ray 242and a line 241 parallel to direct light ray 144 a.)

Light ray 242 traverses the body 184 of the optical redirecting unit 116to the curved edge surface 142 a of the recess 140 a. Light ray 242reflects off the curved edge surface 142 as was described hereinabove.

It should be understood that although not able to be illustrated in FIG.5 because of the lack of granularity, the solar panel assembly 100 andits various components (as with other embodiments of the presenttechnology) are designed to take into account the slight deviations froma straight line of the actual path the light rays take through the solarpanel assembly, an example of a portion of which is illustrated in FIG.5A.

First Embodiment (Method of Manufacture)

Methods of manufacturing solar panel assembly 100, include, but are notlimited to, the following: Appropriately sized single junctionphotovoltaic cells 128 are obtained from a manufacturer thereof (such asone of those referred to in the background section of thisspecification). Material suitable for forming the electrical insulatinglayer 130 is applied to photovoltaic cells 128 via any suitablecombination of direct deposition techniques or growth techniques (suchas forming silicon-oxide layers on the cell 128), or by attaching aninsulating thin sheet or film of polymeric material to the photovoltaiccells 128 via any of adhesive, heat and/or pressure.

In some methods, the electrical conductor 132 is pre-assembled with theelectrical insulator 130 to form one single component that is laterattached to the photovoltaic cells 128 as was described above. In somesuch methods, the electrical conductor 132 is a polymer film withelectrical conductor traces, where the film serves as an insulatinglayer 130 and the traces serve as the conductor 132.

In some methods, the electrical conductor 132 is formed directly on theinsulator 130, by a metal deposition techniques or film applicationtechniques such as sputtering, screen printing, printing, orelectrochemically forming.

In some methods, material suitable for forming the electrical conductor132 is placed on the electrical insulating layer 130.

In some methods, insulator 130 is formed as an integral part of thephotovoltaic cells 128.

In some methods, the photovoltaic cell 128, the insulating layer 130 andthe electrical conductor 132, once assembled would form one solidcomponent.

The electrical conductor 132 electrically interconnects themultiple-junction photovoltaic cells 134. In some methods, themultiple-junction photovoltaic cells 134 are assembled onto theelectrical conductor 132 prior to assembly of the insulator 130 with theelectrical conductor 132 and the photovoltaic cells 128. In othermethods, the multiple-junction photovoltaic cells 134 are assembled ontothe electrical conductor 132 after the previously mentioned assembly insequence. In either case, the multiple-junction photovoltaic cells 134can be pre-packaged (with wire bonds onto a common semiconductor packageor lead frame) to allow for surface mount soldering of themultiple-junction photovoltaic concentrator cells to the underlyingconductor.

The photovoltaic cells 128 and the multiple-junction photovoltaic cells134 are then electrically interconnected together. This is conventionalmanner appropriate for silicon PV cells using solder ribbon to createstrings of photovoltaic cells 128 where the ribbon conductors willultimately be combined to a connector or terminator inside of a junctionbox.

Solder ribbon can also be used to create strings of multiple junctionphotovoltaic cells 134 by creating electrical interconnections betweenthe electrical conductors 132, creating larger strings and ultimatelyproviding a path for electricity outside of the module through ajunction box. The electrical circuit connecting the photovoltaic cells128 can be completely independent of the electrical circuit connectingthe multiple-junction photovoltaic cells 134, with both having terminalsinside the same or in different junction boxes. In the latter case, themodule would have two positive and two negative terminals and would actelectrically as two independent modules with different current andvoltage characteristics and different efficiencies under variousillumination conditions. This would therefore be a four terminalassembly 100 and the power from the two electrically independent moduleswithin the whole module would be combined at some point in theelectrical system or used to power separate loads.

It is also possible to make each module into a two terminal device byusing embedded electronics to perform a DC-DC conversion of any, some orall of the multiple-junction photovoltaic cells 134 and the photovoltaiccells 128 to make it efficient to connect the different cells inparallel or in series. Electronics can be embedded at a module level, atthe string level, or at the photovoltaic cells 128 level.

Once the electrical circuits with terminals have been created for thephotovoltaic cells 128 and the multiple-junction photovoltaic cells 134,the whole assembly (consisting of single junction photovoltaic cells128, insulator 130, conductor 132, and multiple junction photovoltaiccells 134) are laminated between the upper structural layer 124 (e.g.glass) and the lower structural layer 126 (e.g. glass). This laminationcan be done by curing a transparent silicone material between two sheetsof structural layers 124 and 126 with the other elements in place or byreflowing a polymer such as EVA. The lamination process leaves anencapsulation material 136 which envelopes the components(single-junction photovoltaic cells 128, insulator 130, conductor 132,and multiple-junction photovoltaic cells 134) inside the sandwichbetween the two structural layers 124 and 126.

For example, the encapsulation 136 (silicone in this embodiment) can beplaced over the electrical conductor 132 and the lower structural layer126 is placed thereof, sandwiching the single-junction photovoltaiccells 128, the electrical insulator 130, the electrical conductor 132,the multiple-junction photovoltaic cells 134, and the encapsulation 136between the upper 124 and lower 126 structural layers.

Bonding layer 120 (e.g. silicone or EVA) is applied to the free surfaceof the upper structural layer 124 and the optical concentrating units104 are placed thereon adhering them to the upper structural layer 124.

Bonding layer 122 (e.g. silicone or EVA) is applied to the free surfaceof the lower structural layer 126 and the optical redirecting/collectingunits 114 are placed thereon adhering them to the lower structural layer126. The optical collecting unit 118 and the optical redirecting unit116 can be made integrally out of one piece of formed polymer to create114 or they can be an assembly of individually formed pieces bondedtogether.

Second Embodiment

For ease of understanding, the first embodiment—solar panel assembly100—was described with reference to a two-dimensional cross-section(e.g. FIG. 5) of the solar panel assembly 100, showing light raystravelling within the plane of that cross-section. While some actuallight rays do indeed follow these paths, the solar panel assembly 100 isa three-dimensional device. Light rays thus travel in directions otherthan those illustrated in FIG. 5. Thus, with reference to FIG. 9-15, asecond embodiment, a section of a solar panel assembly 1100, isillustrated in three-dimensions to provide additional understanding ofthe present technology.

Referring to FIGS. 9 and 10, solar panel assembly 1100 is similar tosolar panel assembly 100, with some differences. In particular thelenses 1106 on the upper surface 1102 of the optical concentrating units1104 of solar panel assembly 1100 are arranged in five and (a portion ofa sixth) concentric circles (as opposed to in three concentric circlesas was the case with solar panel 100). Similarly, the optical directingunits 1116 of the optical redirecting/collecting units 1114 of solarpanel assembly 1100 have additional recesses 1140 to cooperate with theadditional lenses 1106 of the optical concentrating units 1104.Similarly, there are additional passages 1138 through which the directsunlight rays 1144 are focused in view of the additional lenses 1106 ofthe optical concentrating units 1104.

Referring particularly to FIG. 10, solar panel assembly 1100 has opticalconcentrating units 1104 made of PMMA. The upper surface 1102 of eachoptical concentrating unit 1104 has a series of lenses 1106 arranged inconcentric circles. In between each of the lenses 1106 are flat portions1214. In the center of the upper surface 1101 of each opticalconcentrating unit 1104 is a central circular flat portion 1170. Eachlens 1106 has a convex lens surface 1146 (which is three-dimensionallyillustrated in FIGS. 9 and 10). The optical concentrating units 1104 arebonded to an upper structural layer 1124 made of a sheet of glass by abonding layer 1120 of EVA. Sandwiched between upper structural layer1124 and lower structural layer 1126 (which is also a sheet of glass)are single-junction photovoltaic cells 1128, an electrical insulator1130, an electrical conductor 1132, multiple-junction photovoltaic cells1134, and encapsulation 1136. (Each of these components is similar totheir counterparts in solar panel assembly 100 and will not be describedin further detail herein.) The single-junction photovoltaic cells 1128,the electrical insulator 1130, and the electrical conductor 1132 eachhave a series of holes (1172, 1174, 1176 respectively) therein, togetherforming optical passages 1138.

Optical redirecting/collecting units 1114 of PMMA are bonded to thelower structural surface 1126 by a bonding layer 1122 of EVA. Opticalredirecting/collecting units 1114 each comprise an optical redirectingunit 1116 and an optical collecting unit 1118. Extending upwards fromthe lower surface 1178 of each of the optical redirecting units 1116into the body 1184 thereof are a series of recesses 1140, which arefilled with air. Each recess 1140 has a curved edge surface 1142 (havingthe shape of a portion of a paraboloid) and an edge surface 1186opposite the edge surface 1142 having the shape of a portion of a rightcircular cylinder. Below the optical redirecting unit 1116 is an opticalcollecting unit 1118 (also of PMMA) that has an upper surface 1188sealing the lower surface 1178 of the corresponding optical redirectingunit 1116, and a lower surface 1194 having a curved portion 1198 (havingthe shape of a revolved section of a parabola). Each of the structuresdescribed herein have a similar structure, function, and methods ofassembly and use as with respect to their counterparts in solar panelassembly 100 and will not be described in further detail herein.

Referring to FIG. 9, the path of a direct sunlight ray 1144 throughsolar panel assembly 1100 can be seen. In particular FIG. 9 illustratessuch path in three-dimensions. Direct sunlight ray 1144 impinges on thesurface 1146 of one of the lenses 1106 and is focused (as light ray1148) towards the focus 1150 of the lens 1106, which is at the exit ofthe passage 1138 in the encapsulation 1136. Traversing the focus 1150(as light ray 1152), light ray 1152 continues to travel through thesolar panel assembly 1100 and impinges upon the paraboloidal edgesurface 1142 of a recess 1140. Light ray 1152 reflects off theparaboloidal edge surface 1142 because of total internal reflection andis reflected as light ray 1154 parallel to the axis (not shown) of theparaboloid defining the paraboloidal edge surface 1142. Light ray 1154continues to travel through the solar panel assembly 1100 and impingesupon the revolved parabolic curved portion 1198 of the lower surface1194 of the optical collecting unit 1118. Light ray 1154 reflects offthe revolved parabolic curved portion 1198 because of total internalreflection and is reflected as light ray 1156 towards the focal point(not shown—but located above and near the multiple-junction photovoltaiccell 1134) of the parabola defining the revolved parabolic curvedportion 1198. Light ray 1156 continues to travel through the solar panelassembly 1100 and impinges on the multiple-junction photovoltaic cell1134 for harvesting thereby.

Also shown in FIG. 9 is a second light direct ray 1145 and the path thatit takes through the solar panel assembly 1100 to the multiple-junctionphotovoltaic cell 1134.

FIGS. 11, 11A, 12, 12A, 13, 13A, 14, 14A and 15 assist in providingadditional understanding of the present embodiment. FIG. 15 provides aschematic view illustrating the paths taken by a multitude of directlights rays 1144 impinging on a section of a optical concentrating unit1104 of the solar panel assembly 1100 similar to that in FIGS. 9 and 10.To facilitate understanding this schematic, most of the components ofthe solar panel assembly 1100 are not shown (although they are obviouslypresent). Thus, it can be seen that direct sunlight rays 1144 impinge onthe surface 1146 of one of the lenses 1106 and are focused as light rays1148 towards the focus 1150 of that one of the lenses 1106. Traversingthe focuses 1150 (as light rays 1152), light rays 1152 impinge upon oneof the paraboloidal edge surfaces 1142 and are reflected because oftotal internal reflection as light rays 1154 parallel to the axis of theparaboloid defining that paraboloidal edge surface 1142. Light rays 1154then impinge upon the paraboloidal curved portion 1198 and reflect offthe paraboloidal curved portion 1198 because of total internalreflection as light rays 1156 towards the focal point of theparaboloidal defining the paraboloidal curved portion 1198. Light rays1156 then impinge on the multiple-junction photovoltaic cell 1134 forharvesting thereby.

FIGS. 11-14A provide several schematic views (taken from differentviewpoints) illustrating the paths taken by a multitude of direct lightsrays 1144 impinging on an optical concentrating unit of the solar panelassembly 1100. Again, to facilitate understanding these schematics, mostof the components of the solar panel assembly 1100 are not shown(although they are obviously present). Thus, it can be seen that directsunlight rays 1144 impinge on the surface 1146 of one of the lenses 1106and are focused as light rays 1148 towards the focus 1150 of that one ofthe lenses 1106. Traversing the focuses 1150 (as light rays 1152), lightrays 1152 impinge upon one of the paraboloidal edge surfaces 1142 andare reflected because of total internal reflection as light rays 1154parallel to the axis of the paraboloid defining that paraboloidal edgesurface 1142. Light rays 1154 then impinge upon the revolved paraboliccurved portion 1198 and reflect off the revolved parabolic curvedportion 1198 because of total internal reflections as light rays 1156towards the focal point of the parabola defining the revolved paraboliccurved portion 1198. Light rays 1156 then impinge on themultiple-junction photovoltaic cell 1134 for harvesting thereby.

In this embodiment, direct light rays (not shown) impinging upon thecentral flat portion 1170 of the upper surface 1102 of the opticalcollecting unit 1104 of the solar panel assembly 1100 impinge upon thesingle-junction photovoltaic cell 1128 (shown only in FIGS. 9-10) forharvesting.

No diffuse light rays have been shown imping upon the solar panelassembly 1100 in FIGS. 9-15 in order to facilitate understanding. As wasdescribed above with respect to the first embodiment, in thisembodiment, such light diffuse light rays would generally ultimatelyimpinge about the single-junction photovoltaic cell 1128 for harvesting.

Third Embodiment

Referring to FIG. 16, there is illustrated a third embodiment, solarpanel assembly 2100, shown in cross-section. Solar panel assembly 2100is similar to solar panel assembly 100, with some differences. Inparticular, the optical collecting element of this embodiment is acompound structure, as is further described herein below.

Solar panel assembly 2100 has optical concentrating units 2104 of PMMA.The upper surface 2102 of each optical concentrating unit 2104 has aseries of lenses 2106 arranged in concentric circles. In the center ofthe upper surface 2102 of each optical concentrating unit 2104 is acentral circular flat portion 2170. Each lens 2106 has a convex lenssurface 2146. The optical concentrating units 2104 are bonded to anupper structural layer 2124 (made of a sheet of glass) by bonding layer2120 of EVA. Sandwiched between upper structural layer 2124 and lowerstructural layer 2126 (which is also a sheet of glass) aresingle-junction photovoltaic cells 2128, an electrical insulator 2130,an electrical conductor 2132 (illustrated for simplicity in FIG. 16 as asingle layer), multiple-junction photovoltaic cells 2134, andencapsulation 2136. In this embodiment, the upper surface 2258 has aring-shaped recess 2252 (when viewed from above) therein surrounding themultiple-junction photovoltaic cell 2134. The ring-shaped recess 2252has a curved bottom surface 2254 being parabolic in cross section. (Eachof these components is otherwise similar to their counterparts in solarpanel assembly 100 and will not be described in further detail herein.)The single junction photovoltaic cells 2128, the electrical insulator2130, and the electrical conductor 2132 each have a series of holesforming optical passages 2138.

Optical redirecting/collecting units 2114 of PMMA are bonded to thelower structural surface 2126 by a bonding layer 2122 of EVA. Opticalredirecting/collecting units 2118 each comprise an optical redirectingunit 2116 and an optical collecting unit 2114. Extending upwards fromthe lower surface 2178 of each of the optical redirecting units 2116into the body 2184 thereof are a series of recesses 2140, which arefiled with air. Each recess 2140 has a curved edge surface 2142 (havingthe shape of a portion of a paraboloid) and an edge surface 2186opposite the edge surface 2142 having the shape of a portion of a rightcircular cylinder. Below the optical redirecting unit 2116 is an opticalcollecting unit 2118 (also of PMMA) that has an upper surface 2188sealing the lower surface 2178 of the corresponding optical redirectingunit 2116, and a lower surface 2194 having a curved portion 2198 (havingthe shape of a portion of a paraboloid). Each of the structuresdescribed herein have a similar structure, function, and methods ofassembly and use as with respect to their counterparts in solar panelassembly 100 and will not be described in further detail herein.

In FIG. 16, the path of direct sunlight rays 2144 through solar panelassembly 2100 can be seen. In this respect, certain direct sunlight rays2144 c,d have a path that is similar to that of the path of the directlight rays 144 shown in FIG. 5. Thus, direct sunlight rays 2144 c,dimpinge on the surface 2146 c,d (respectively) of one of the lenses 2106c,d (respectively) and are focused (as light rays 2148 c,d(respectively)) towards the focus 2150 c,d (respectively) of the lenses2106 c,d (respectively), which are at the exit of the passages 2138 c,d(respectively) in the encapsulation 2136. Traversing the focus 2150 c,d(respectively) (as light rays 2152 c,d (respectively)), light rays 2152c,d continue to travel through the solar panel assembly 2100 and impingeupon the paraboloidal edge surfaces 2142 c,d (respectively) of recesses2140 c,d (respectively). Light rays 2152 c,d reflects off theparaboloidal edge surfaces 2142 c,d (respectively) because of totalinternal reflection and are reflected as light rays 2154 c,d(respectively) parallel to the axis (not shown) of the paraboloidsdefining the paraboloidal edge surface 2142 c,d. (The focuses of theparaboloids defining the paraboloidal edge surfaces 2142 c,d are in thisembodiment coincident with the focus 2150 c,d of the lenses 2106 c,drespectively.) Light rays 2154 c,d continue to travel through the solarpanel assembly 2100 and impinge upon the revolved parabolic curvedportion 2198 of the lower surface 2194 of the optical collecting unit2118. Light rays 2154 c,d reflect off the revolved parabolic curvedportion 2198 because of total internal reflection and are reflected aslight rays 2156 c,d (respectively) towards the focal point (notshown—but located above and near the multiple-junction photovoltaic cell2134) of the parabola defining the revolved paraboloic curved portion2198. Light rays 2156 c,d (respectively) continue to travel through thesolar panel assembly 2100 and impinge on the multiple-junctionphotovoltaic cell 2134 for harvesting thereby.

However, certain direct sunlight rays 2144 a,b have a path that differsslightly from the path described previously with respect to directsunlight rays 2144 c,d. Direct sunlight rays 2144 a,b impinge on thesurface 2146 a of one of the lenses 2106 a and are focused (as lightrays 2148 a,b (respectively)) towards the focus 2150 a of the lens 2106a, which is at the exit of the passages 2138 a in the encapsulation2136. Traversing the focus 2150 a (as light rays 2152 a,b(respectively)), light rays 2152 a,b continue to travel through thesolar panel assembly 2100 and impinge upon the paraboloidal edge surface2142 a of recess 2140 a. Light rays 2152 a,b reflect off theparaboloidal edge surface 2142 a because of total internal reflectionand are reflected as light rays 2154 a,b parallel to the axis (notshown) of the paraboloid defining the paraboloidal edge surface 2142 a.(The focuses of the paraboloids defining the paraboloidal edge surface2142 a are in this embodiment coincident with the focus 2150 a of thelens 2106 a.) Light rays 2154 a,b continue to travel through the solarpanel assembly 2100 and impinge upon the revolved parabolic curvedportion 2198 of the lower surface 2194 of the optical collecting unit2118. Light rays 2154 a,b reflect off the revolved parabolic curvedportion 2198 because of total internal reflection and are reflected aslight rays 2156 a,b (respectively) towards the focal point (notshown—but located above the multiple-junction photovoltaic cell 2134) ofthe parabola defining the revolved parabolic curved portion 2198. Lightrays 2156 a,b (respectively) continue to travel through the solar panelassembly 2100 and impinge on the curved bottom surface 2254 of recess2252 in the lower structure layer 2126. Light rays 2156 a,b reflect offthe curved bottom surface 2254 because of a mirror coating on thesurface of the recess and are reflected as light rays 2256 a,b(respectively) towards the multiple-junction photovoltaic cell 2134.Light rays 2256 a,b (respectively) continue to travel through the solarpanel assembly 2100 and impinge on the multiple-junction photovoltaiccell 2134 for harvesting thereby.

In this embodiment, direct light rays (not shown) impinging upon thecentral flat portion 2170 of the upper surface 2102 of the opticalcollecting 2104 of the solar panel assembly 2100 impinge upon thesingle-junction photovoltaic cell 2128.

No diffuse light rays have been shown impinging upon the solar panelassembly 2100 in FIG. 16 in order to facilitate understanding. As wasdescribed above with respect to the first embodiment, in thisembodiment, such light diffuse light rays would generally ultimatelyimpinge about the single-junction photovoltaic cell 2128 for harvesting.

Fourth Embodiment

Referring to FIG. 17, there is illustrated a fourth embodiment, solarpanel assembly 3100, shown in cross-section. Solar panel assembly 3100is similar to solar panel assembly 100, with some differences. Inparticular, this embodiment has no optical collecting element.

Solar panel assembly 3100 has optical concentrating units 3104 of PMMA.The upper surface 3102 of each optical concentrating unit 3104 has aseries of lenses 3106 arranged in concentric circles. In the center ofthe upper surface 3102 of each optical concentrating unit 3104 is acentral circular flat portion 3170. Each lens 3106 has a convex lenssurface 3146. The optical concentrating units 3104 are bonded to an(upper) structural layer 3124 (made of a sheet of glass) by bondinglayer 3120 of EVA. Sandwiched between upper structural layer 3124 and anoptical redirecting unit 3116 (which is in this embodiment is made ofglass) are single junction photovoltaic cells 3128, an electricalinsulator 3130, an electrical conductor 3132 (all illustrated forsimplicity in FIG. 17 as a single layer), multiple-junction photovoltaiccells 3134, and encapsulation 3136. (Each of these components isotherwise similar to their counterparts in solar panel assembly 100 andwill not be described in further detail herein.) The single-junctionphotovoltaic cells 3128, the electrical insulator 3130, and theelectrical conductor 3132 each have a series of holes forming opticalpassages 3138.

Optical redirecting units 3116 each have a series of downward annularstraight walled projections 3141 made of PMMA. At the lower end of eachprojection 3141 is a curved surface 3143, which is coated with areflective material such as aluminium or silver to form a mirror.

In FIG. 17, the path of direct sunlight rays 3144 through solar panelassembly 3100 can be seen. Direct sunlight rays 3144 impinge on thesurface 3146 of one of the lenses 3106 and are focused (as light rays3148) towards the focus 3150 of the lenses 3106, which are at the exitof the passages 3138 in the encapsulation 3136. Traversing the focus3150 (as light rays 3152), light rays 3152 continue to travel throughoptical redirecting unit 3116 and the annual projections 3141 thereofand impinge upon the parabolic mirrored surfaces 3143. Light rays 3152reflect off the curved mirrored surfaces 3143 and are reflected as lightrays 3154 towards the focal point (not shown—but appropriately locatedwith respect to the multiple-junction photovoltaic cell 3134 such thatlight rays impinging thereon are focused such that they intersect themultiple-junction photovoltaic cell 3134) of the curved mirrored surface3143. Light rays 3154 continue to travel and impinge on themultiple-junction photovoltaic cell 3134 for harvesting thereby.

In this embodiment, direct light rays (not shown) impinging upon thecentral flat portion 3170 of the upper surface 3102 of the opticalcollecting unit 3104 of the solar panel assembly 3100 impinge upon thesingle-junction photovoltaic cell 3128.

No diffuse light rays have been shown imping upon the solar panelassembly 3100 in FIG. 17 in order to facilitate understanding. As wasdescribed above with respect to the first embodiment, in thisembodiment, such light diffuse light rays would generally ultimatelyimpinge about the single-junction photovoltaic cell 3128 for harvesting.

Fifth Embodiment

Referring to FIG. 18, there is illustrated a fifth embodiment, solarpanel assembly 4100, shown in cross-section. Solar panel assembly 4100is similar to solar panel assembly 100, with some differences. Inparticular, the focused collected direct rays enter the upper surface4270 of the multiple junction photovoltaic cell 4134, as is furtherdescribed herein below.

Solar panel assembly 4100 has optical concentrating units 4104 of PMMA.The upper surface 4102 of each optical concentrating unit 4104 has aseries of lenses 4106 (4106 a, 4106 b, 4106 c, 4106 d, 4106 e, 4106 f)arranged in concentric circles. In the center of the upper surface 4102of each optical concentrating unit 4104 is a central circular flatportion 4170. Each lens 4106 has a convex lens surface 4146 (4146 a,4146 b, 4146 c, 4146 d, 4146 e, 4146 f). The optical concentrating units4104 are bonded to an upper structural layer 4124 (made of a sheet ofglass) by bonding layer 4120 of EVA. Sandwiched between upper structurallayer 4124 and lower structural layer 4126 (which is also a sheet ofglass) are single-junction photovoltaic cells 4128, an electricalinsulator 4130, an electrical conductor 4132 (illustrated for simplicityin FIG. 18 as a single layer), multiple-junction photovoltaic cells4134, and encapsulation 4136. (Each of these components is otherwisesimilar to their counterparts in solar panel assembly 100 and, except asfollows, will not be described in further detail herein.) In thisembodiment, the lower surface 4272 of the upper structural layer 4124has a hemispherical recess 4262 therein. The exposed “dome” of therecess is coated with a layer of aluminum metal 4264 forming a highlyreflective mirrored surface. Between the aluminum metal layer 4264 andthe glass of the upper structural layer 4124 and the conductor 4132 is alayer of aluminum oxide 4266, which acts as an insulator. The insulator4130 and the conductor 4132 have an opening 4274 therein that isslightly larger than the hemispherical recess 4262 to allow light toenter the recess as is described below.

Optical redirecting/collecting units 4114 of PMMA are bonded to thelower structural surface 4126 by a bonding layer 4122 of EVA. Opticalredirecting/collecting unites 4114 each comprise an optical redirectingunit 4116 and an optical collecting unit 4118. Extending upwards fromthe lower surface 4178 of each of the optical redirecting units 4116into the body 4184 are a series of recesses 4140, which are filed withair. Each recess 4140 has a curved edge surface 4142 (having the shapeof a portion of a paraboloid) and an edge surface 4186 opposite the edgesurface 4142 having the shape of a portion of a right circular cylinder.Below the optical redirecting unit 4116 is an optical collecting unit4118 (also of PMMA) that has an upper surface 4188 sealing the lowersurface 4178 of the corresponding optical redirecting unit 4116, and alower surface 4194 having a curved portion 4198 (having the shape of arevolved section of a parabola). Each of the structures described hereinhave a similar structure, function, and methods of assembly and use aswith respect to their counterparts in solar panel assembly 100 and willnot be described in further detail herein.

In FIG. 18, the path of direct sunlight rays 4144 through solar panelassembly 4100 can be seen. In this respect, direct sunlight rays 4144a,b impinge on the surface 4146 a of the lens 4106 a and are focused (aslight rays 4148 a,b (respectively)) towards the focus 4150 a of the lens4106 a, which is at the exit of the passages 4138 a in the encapsulation4136. Traversing the focus 4150 a (as light rays 4152 a,b(respectively)), light rays 4152 a,b continue to travel through thesolar panel assembly 4100 and impinge upon the paraboloidal edge surface4142 a of recess 4140 a. Light rays 4152 a,b reflect off theparaboloidal edge surface 4142 a because of total internal reflectionand are reflected as light rays 4154 a,b parallel to the axis (notshown) of the paraboloid defining the paraboloidal edge surface 4142 a.(The focus of the paraboloid defining the paraboloidal edge surface 4142a is, in this embodiment, coincident with the focus 4150 a of the lens4106 a.) Light rays 4154 a,b continue to travel through the solar panelassembly 4100 and impinge upon the revolved parabolic curved portion4198 of the lower surface 4194 of the optical collecting unit 4118.Light rays 4154 a,b reflect off the revolved parabolic curved portion4198 because of total internal reflection and are reflected as lightrays 4156 a,b (respectively) towards the focal point 4268 a of theparabola defining the revolved paraboloic curved portion 4198. Lightrays 4156 a,b continue to travel past the focus 4268 a (and diverge) andimpinge on the aluminum metal layer 4264. The aluminum metal layer 4264acts as a reflector and light rays 4256 a,b reflect thereof towards theupper surface 4270 of the multiple-junction photovoltaic cells 4134 forharvesting thereby.

Similarly, direct sunlight rays 4144 d,e impinge on the surfaces 4146d,e of the lenses 4106 d,e (respectively) and are focused (as light rays4148 d,e (respectively)) towards the focuses 4150 d,e of the lenses 4106d,e (respectively), which are at the exit of the passages 4138 d,e(respectively) in the encapsulation 4136. Traversing the focuses 4150d,e (as light rays 4152 d,e (respectively)), light rays 4152 d,econtinue to travel through the solar panel assembly 4100 and impingeupon the paraboloidal edge surface 4142 d,e of recesses 4140 d,e(respectively). Light rays 4152 d,e (respectively) reflect off theparaboloidal edge surfaces 4142 d,e (respectively) because of totalinternal reflection and are reflected as light rays 4154 d,e(respectively) parallel to the axes (not shown) of the paraboloidsdefining the paraboloidal edge surfaces 4142 d,e (respectively). (Thefocuses of the paraboloids defining the paraboloidal edge surfaces 4142d,e are, in this embodiment, coincident with the focuses 4150 d,e of thelenses 4106 d,e (respectively).) Light rays 4154 d,e continue to travelthrough the solar panel assembly 4100 and impinge upon the revolvedparabolic curved portion 4198 of the lower surface 4194 of the opticalcollecting unit 4118. Light rays 4154 d,e reflect off the revolvedparabolic curved portion 4198 because of total internal reflection andare reflected as light rays 4156 d,e (respectively) towards the focalpoint 4268 b of the parabola defining the revolved paraboloic curvedportion 4198. Light rays 4156 d,e continue to travel past the focus 4268b (and diverge) and impinge on the aluminum metal layer 4264. Thealuminum metal layer 4264 acts as a reflector and light rays 4256 d,ereflect thereof towards the upper surface 4270 of the multiple-junctionphotovoltaic cells 4134 for harvesting thereby.

In this embodiment, direct light rays (not shown) impinging upon thecentral flat portion 4170 of the upper surface 4102 of the opticalconcentrating unit 4104 of the solar panel assembly 4100 impinge uponthe single-junction photovoltaic cell 4128.

No diffuse light rays have been shown imping upon the solar panelassembly 4100 in FIG. 18 in order to facilitate understanding. As wasdescribed above with respect to the first embodiment, in thisembodiment, such light diffuse light rays would generally ultimatelyimpinge about the single-junction photovoltaic cell 4128 for harvesting.

Additional Disclosure

FIG. 19 is a close-up cross sectional schematic view of solar panelassembly 5100 illustrating heat dissipation in some embodiments of thepresent technology. Specifically boding layers 5120, 5122; structurallayers 5124, 5126; single-junction photovoltaic cell 5128; electricalinsulator 5130; electrical conductor 5132; multiple-junctionphotovoltaic cell 5134; and encapsulation 5136 (which may be similar tothose described hereinabove) are shown in FIG. 19. In embodiments of thepresent technology that function as illustrated in this schematic, themajority of the thermal energy 5260 generated by the operation of themultiple-junction photovoltaic cell 5134 is dissipated by thesingle-junction photovoltaic cell 5128. This may occur in embodimentswhere the single junction photovoltaic cell 5128 is more thermallyconductive than is the electrical insulator 5130 and the electricalconductor 5132. Such may be the case in one of the embodiments describedhereinabove where the thermal conductivity, geometry, and sizing of thevarious components (e.g. structural layers 5124, 5126; single-junctionphotovoltaic cell 5128; electrical insulator 5130; electrical conductor5132; and encapsulant 5136) is such that this occurs. Such may also (orin addition) be the case owing to a change in the materials of thevarious components. In a non-limiting example, where the electricalinsulator 5130 is made of aluminum nitride (AlN)—which is a goodelectrical insulator and a good thermal conductor and the electricalconductor 5132 is a made of Titanium—which is a good electricalconductor but a poor thermal conductor—this may occur.

FIG. 20 is a close-up cross sectional schematic view of solar panelassembly 6100 illustrating heat dissipation in some embodiments of thepresent technology. Specifically boding layers 6120, 6122; structurallayers 6124, 6126; single-junction photovoltaic cell 6128; electricalinsulator 6130; electrical conductor 6132; multiple-junctionphotovoltaic cell 6134; and encapsulation 6136 (which may be similar tothose described hereinabove) are shown in FIG. 20. In embodiments of thepresent technology that function as illustrated in this schematic, themajority of the thermal energy 6260 generated by the operation of themultiple-junction photovoltaic cell 6134 is dissipated by the electricalconductor 6132. This may occur in embodiments where the electricalconductor 6132 is more thermally conductive than is the electricalinsulator 6130 and the single-junction photovoltaic cell 6128. Such maybe the case in one of the embodiments described hereinabove where thethermal conductivity, geometry, and sizing of the various components(e.g. structural layers 6124, 6126; single-junction photovoltaic cell6128; electrical insulator 6130; electrical conductor 6132; andencapsulation 6136) is such that this occurs. Such may also (or inaddition) be the case owing to a change in the materials of the variouscomponents. In a non-limiting example, where the electrical conductor6132 is made of copper metal (Cu)—which is a good electrical conductorand a good thermal conductor and the electrical insulator 6130 is a madeof biaxially-oriented polyethylene terephthalate (BoPET—“Mylar”™)—whichis both a good electrical and thermal insulator.

FIG. 21 is a close-up to plan schematic view of the lenses 7106 a solarpanel assembly 7100 of the present technology illustrating the lenses7106 being in a Cartesian array.

FIG. 22 is a close-up to plan schematic view of the lenses 8106 a solarpanel assembly 8100 of the present technology illustrating the lenses8106 being in a non-regularly-spaced algorithmically-determined array.

FIG. 23 is a close-up to plan schematic view of the lenses 9106 a solarpanel assembly 9100 of the present technology illustrating the lenses9106 being in a hexagonal array.

FIG. 24 is a perspective schematic view of a solar panel assembly 10100of the present technology illustrating the lenses 10106 being in aclosely-packed Cartesian array.

The lenses 10106 are square-shaped in plan view and there is little orno space 10107 between them (depending on the embodiment).

FIGS. 25 and 25A show a plan view of an electrical conductor 11132 andportions of an electrical insulator 11130 suitable for use in someembodiments of the present technology. As can be seen in FIG. 25, theelectrical conductor 11132 is shaped to form two different current paths11162, 11164 of an electrical circuit (unlabeled) that includes themultiple-junction photovoltaic cells 11134 associated with the asingle-junction photovoltaic cell (not shown). The electrical circuithas “positive” current path 11162 connected to the positive terminal(unlabelled) of each of the multiple junction photovoltaic cells 11134and a “negative” current path connected to the negative terminals 11166of each of the multiple-junction photovoltaic cells 11134 (see also FIG.25A showing a close-up view of these connections). Also shown in FIG. 25are the terminals 11163, 11165 of the conductor for the single junctionphotovoltaic cell (not shown). In this construction, the electricalcircuit formed for the single-junction photovoltaic cell is isolatedfrom (in addition to being electrically separate from) that formed forthe multiple junction photovoltaic cells 11134. The electrical conductor11132 has a series of openings 11176 therein.

FIGS. 26 and 26A show a plan view of an electrical conductor 12132 andportions of an electrical insulator 12130 suitable for use in someembodiments of the present technology. As can be seen in FIG. 26, theelectrical conductor 12132 is shaped to form two different current paths12162, 12164 of an electrical circuit (unlabeled) that includes themultiple-junction photovoltaic cells 12134 associated with the asingle-junction photovoltaic cell (not shown). The electrical circuithas “positive” current path 12162 connected to the positive terminal(unlabelled) of each of the multiple junction photovoltaic cells 12134and a “negative” current path connected to the negative terminals 12166of each of the multiple-junction photovoltaic cells 12134 (see also FIG.26A showing a close-up view of these connections). Also shown in FIG. 26are the terminals 12163, 12165 of the conductor for the single junctionphotovoltaic cell (not shown). In this construction, the electricalcircuit formed for the single junction photovoltaic cell is intertwinedwith (although electrically separate from) that formed for themultiple-junction photovoltaic cells 12134. The electrical conductor12132 has a series of openings 12176 therein.

Modifications and improvements to the above-described embodiments of thepresent technology may become apparent to those skilled in the art. Theforegoing description is intended to be exemplary rather than limiting.The scope of the present technology is therefore intended to be limitedsolely by the scope of the appended claims.

1. A device for harvesting direct light and diffuse light from a lightsource, the device comprising: a first photovoltaic cell, the firstphotovoltaic cell having an upper surface, a lower surface, and an arrayof optical passages therein in optical communication with the uppersurface and the lower surface; an array of optical concentratingelements above the upper surface of the first photovoltaic cell defininga light acceptance area, each of the optical concentrating elementsbeing associated with one of the optical passages, each of the opticalconcentrating elements being structured and arranged to concentratedirect light from the light source impinging on that opticalconcentrating element towards the one of the optical passages associatedwith that optical concentrating element, the concentrated direct lightpassing through the first photovoltaic cell via the optical passage andexiting the first photovoltaic cell via the lower surface as anon-parallel beam of light, diffuse light from the light source passingthrough the array of optical concentrating elements to the upper surfaceof the first photovoltaic cell and entering the first photovoltaic cellfor harvesting thereby; and an array of optical redirecting elementsbelow the lower surface of the first photovoltaic cell, each of theredirecting elements being associated with one of the optical passages,each of the redirecting elements receiving the beam of light from theoptical passage with which that redirecting element is associated andredirecting the beam of light optically towards a second photovoltaiccell for harvesting thereby, the second photovoltaic cell having anactive area receiving the beams of the light, the active area of thesecond photovoltaic cell being smaller than the light acceptance areadefined by the array of optical concentrating elements by aconcentration factor.
 2. The device of claim 1, wherein the secondphotovoltaic cell has an upper surface and a lower surface, and thebeams of light from the array of optical redirecting elements enter thesecond photovoltaic cell through the lower surface thereof. 3.(canceled)
 4. The device of claim 2, wherein the upper surface of thesecond photovoltaic cell is adjacent the lower surface of the firstphotovoltaic cell.
 5. The device of claim 1, wherein the secondphotovoltaic cell is vertically spaced apart from the first photovoltaiccell and has an upper surface and a lower surface, the beams of lightfrom the array of optical redirecting elements entering the secondphotovoltaic cell through the upper surface thereof.
 6. (canceled) 7.The device of claim 1, further comprising an optical collecting element,the optical collecting element receiving the beams of the light from thearray of optical redirecting elements and reorienting the beamsoptically towards the second photovoltaic cell.
 8. The device of claim7, wherein, the optical collecting element reorients the beams of lightdirectly towards the second photovoltaic cell.
 9. The device of claim 1,wherein the redirecting elements redirect the beams of light directlytowards the second photovoltaic cell.
 10. The device of claim 1, whereinthe optical concentrating elements are lenses.
 11. The device of claim10, wherein the lenses are arranged in a first pattern including a firstseries of concentric circles having a first common center, and for a oneof the first series of concentric circles the lenses of that one of thefirst series of concentric circles are of a same surface area, thesurface of the lenses increasing progressing away from the first commoncenter.
 12. The device of claim 10, wherein the lenses are arranged in ahexagonal array.
 13. (canceled)
 14. The device of claim 10, wherein thelenses are arranged in a non-regularly-spaced array.
 15. The device ofclaim 1, wherein the optical passages are openings through the firstphotovoltaic cell.
 16. (canceled)
 17. The device of claim 1, wherein theoptical redirecting elements are reflectors and redirecting the beam oflight occurs via total internal reflection. 18-21. (canceled)
 22. Thedevice of claim 11, wherein the optical redirecting elements arearranged in a second pattern including a second series of concentriccircles having a second common center. 23-29. (canceled)
 30. The deviceof claim 10, wherein the lenses are formed in a first single layer ofmaterial
 31. The device of claim 17, wherein the reflectors are formedin a second single layer of material.
 32. The device of claim 25,wherein the revolved reflective surface is formed in a third singlelayer of material.
 33. The device of claim 1, wherein the secondphotovoltaic cell is in thermal communication with the firstphotovoltaic cell, and the first photovoltaic cell is the primary heatsink of the second photovoltaic cell.
 34. The device of claim 1, whereinthe second photovoltaic cell is in thermal communication and electricalcommunication with an electric circuit sandwiched within the device, theelectric circuit being the primary heat sink of the second photovoltaiccell, the electric circuit being electrically separated from the firstphotovoltaic cell by an electrical insulator.
 35. The device of claim 1,wherein environmental albedo light enters the lower surface of the firstphotovoltaic cell for harvesting thereby.